fix std log (#12470)

related to
- https://github.com/nushell/nushell/pull/12196

# Description
while i'm 100% okey with the original intent behind
https://github.com/nushell/nushell/pull/12196, i think the PR did
introduce two unintended things:
- extra parentheses that make the `log.nu` module look like Lisp lol
- a renaming of the `NU_LOG_LEVEL` environment variable to
`NU_log-level`. this breaks previous usage of `std log` and, as it's not
mentionned at all in the PR, i thought it was not intentional 😋

# User-Facing Changes
users can now control `std log` with `$env.NU_LOG_LEVEL`

# Tests + Formatting
the "log" tests have been fixed as well.

# After Submitting

crates/nu-std/tests/logger_tests/test_basic_commands.nu

@@ -6,9 +6,9 @@ def run [
     --short
 ] {
     if $short {
-        ^$nu.current-exe --no-config-file --commands $'use std; NU_log-level=($system_level) std log ($message_level) --short "test message"'
+        ^$nu.current-exe --no-config-file --commands $'use std; NU_LOG_LEVEL=($system_level) std log ($message_level) --short "test message"'
     } else {
-        ^$nu.current-exe --no-config-file --commands $'use std; NU_log-level=($system_level) std log ($message_level) "test message"'
+        ^$nu.current-exe --no-config-file --commands $'use std; NU_LOG_LEVEL=($system_level) std log ($message_level) "test message"'
     }
     | complete | get --ignore-errors stderr
 }

crates/nu-std/tests/logger_tests/test_log_custom.nu

@@ -12,12 +12,12 @@ def run-command [
 ] {
     if ($level_prefix | is-empty) {
         if ($ansi | is-empty) {
-            ^$nu.current-exe --no-config-file --commands $'use std; NU_log-level=($system_level) std log custom "($message)" "($format)" ($log_level)'
+            ^$nu.current-exe --no-config-file --commands $'use std; NU_LOG_LEVEL=($system_level) std log custom "($message)" "($format)" ($log_level)'
         } else {
-            ^$nu.current-exe --no-config-file --commands $'use std; NU_log-level=($system_level) std log custom "($message)" "($format)" ($log_level) --ansi "($ansi)"'
+            ^$nu.current-exe --no-config-file --commands $'use std; NU_LOG_LEVEL=($system_level) std log custom "($message)" "($format)" ($log_level) --ansi "($ansi)"'
         }
     } else {
-        ^$nu.current-exe --no-config-file --commands $'use std; NU_log-level=($system_level) std log custom "($message)" "($format)" ($log_level) --level-prefix "($level_prefix)" --ansi "($ansi)"'
+        ^$nu.current-exe --no-config-file --commands $'use std; NU_LOG_LEVEL=($system_level) std log custom "($message)" "($format)" ($log_level) --level-prefix "($level_prefix)" --ansi "($ansi)"'
     }
     | complete | get --ignore-errors stderr
 }

crates/nu-std/tests/logger_tests/test_log_format_flag.nu

@@ -10,9 +10,9 @@ def run-command [
     --short
 ] {
     if $short {
-        ^$nu.current-exe --no-config-file --commands $'use std; NU_log-level=($system_level) std log ($message_level) --format "($format)" --short "($message)"'
+        ^$nu.current-exe --no-config-file --commands $'use std; NU_LOG_LEVEL=($system_level) std log ($message_level) --format "($format)" --short "($message)"'
     } else {
-        ^$nu.current-exe --no-config-file --commands $'use std; NU_log-level=($system_level) std log ($message_level) --format "($format)" "($message)"'
+        ^$nu.current-exe --no-config-file --commands $'use std; NU_LOG_LEVEL=($system_level) std log ($message_level) --format "($format)" "($message)"'
     }
     | complete | get --ignore-errors stderr
 }

crates/nu-std/tests/logger_tests/test_logger_env.nu

@@ -3,38 +3,38 @@ use std log *
 
 #[test]
 def env_log-ansi [] {
-    assert equal ((log-ansi).CRITICAL) (ansi red_bold)
-    assert equal ((log-ansi).ERROR) (ansi red)
-    assert equal ((log-ansi).WARNING) (ansi yellow)
-    assert equal ((log-ansi).INFO) (ansi default)
-    assert equal ((log-ansi).DEBUG) (ansi default_dimmed)
+    assert equal (log-ansi).CRITICAL (ansi red_bold)
+    assert equal (log-ansi).ERROR (ansi red)
+    assert equal (log-ansi).WARNING (ansi yellow)
+    assert equal (log-ansi).INFO (ansi default)
+    assert equal (log-ansi).DEBUG (ansi default_dimmed)
 }
 
 #[test]
 def env_log-level [] {
-    assert equal ((log-level).CRITICAL) 50
-    assert equal ((log-level).ERROR) 40
-    assert equal ((log-level).WARNING) 30
-    assert equal ((log-level).INFO) 20
-    assert equal ((log-level).DEBUG) 10
+    assert equal (log-level).CRITICAL 50
+    assert equal (log-level).ERROR 40
+    assert equal (log-level).WARNING 30
+    assert equal (log-level).INFO 20
+    assert equal (log-level).DEBUG 10
 }
 
 #[test]
 def env_log-prefix [] {
-    assert equal ((log-prefix).CRITICAL) "CRT"
-    assert equal ((log-prefix).ERROR) "ERR"
-    assert equal ((log-prefix).WARNING) "WRN"
-    assert equal ((log-prefix).INFO) "INF"
-    assert equal ((log-prefix).DEBUG) "DBG"
+    assert equal (log-prefix).CRITICAL "CRT"
+    assert equal (log-prefix).ERROR "ERR"
+    assert equal (log-prefix).WARNING "WRN"
+    assert equal (log-prefix).INFO "INF"
+    assert equal (log-prefix).DEBUG "DBG"
 }
 
 #[test]
 def env_log-short-prefix [] {
-    assert equal ((log-short-prefix).CRITICAL) "C"
-    assert equal ((log-short-prefix).ERROR) "E"
-    assert equal ((log-short-prefix).WARNING) "W"
-    assert equal ((log-short-prefix).INFO) "I"
-    assert equal ((log-short-prefix).DEBUG) "D"
+    assert equal (log-short-prefix).CRITICAL "C"
+    assert equal (log-short-prefix).ERROR "E"
+    assert equal (log-short-prefix).WARNING "W"
+    assert equal (log-short-prefix).INFO "I"
+    assert equal (log-short-prefix).DEBUG "D"
 }
 
 #[test]