Removes unnecessary cwd and pipeline from various tests (#9202)

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Cleans up various tests that unnecessarily use the `cwd` argument of
`nu!`, and the `pipeline` function for single line commands. Also
replaces some unnecessary raw strings with normal strings. Part of
#8670.

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crates/nu-command/tests/commands/each.rs

@@ -2,50 +2,35 @@ use nu_test_support::nu;
 
 #[test]
 fn each_works_separately() {
-    let actual = nu!(
-        cwd: "tests/fixtures/formats",
-        "echo [1 2 3] | each { |it| echo $it 10 | math sum } | to json -r"
-    );
+    let actual = nu!("echo [1 2 3] | each { |it| echo $it 10 | math sum } | to json -r");
 
     assert_eq!(actual.out, "[11,12,13]");
 }
 
 #[test]
 fn each_group_works() {
-    let actual = nu!(
-        cwd: "tests/fixtures/formats",
-        "echo [1 2 3 4 5 6] | group 3 | to json --raw"
-    );
+    let actual = nu!("echo [1 2 3 4 5 6] | group 3 | to json --raw");
 
     assert_eq!(actual.out, "[[1,2,3],[4,5,6]]");
 }
 
 #[test]
 fn each_window() {
-    let actual = nu!(
-        cwd: "tests/fixtures/formats",
-        "echo [1 2 3 4] | window 3 | to json --raw"
-    );
+    let actual = nu!("echo [1 2 3 4] | window 3 | to json --raw");
 
     assert_eq!(actual.out, "[[1,2,3],[2,3,4]]");
 }
 
 #[test]
 fn each_window_stride() {
-    let actual = nu!(
-        cwd: "tests/fixtures/formats",
-        "echo [1 2 3 4 5 6] | window 3 -s 2 | to json --raw"
-    );
+    let actual = nu!("echo [1 2 3 4 5 6] | window 3 -s 2 | to json --raw");
 
     assert_eq!(actual.out, "[[1,2,3],[3,4,5]]");
 }
 
 #[test]
 fn each_no_args_in_block() {
-    let actual = nu!(
-        cwd: "tests/fixtures/formats",
-        "echo [[foo bar]; [a b] [c d] [e f]] | each {|i| $i | to json -r } | get 1"
-    );
+    let actual = nu!("echo [[foo bar]; [a b] [c d] [e f]] | each {|i| $i | to json -r } | get 1");
 
     assert_eq!(actual.out, r#"{"foo": "c","bar": "d"}"#);
 }
@@ -53,7 +38,6 @@ fn each_no_args_in_block() {
 #[test]
 fn each_implicit_it_in_block() {
     let actual = nu!(
-        cwd: "tests/fixtures/formats",
         "echo [[foo bar]; [a b] [c d] [e f]] | each { |it| nu --testbin cococo $it.foo } | str join"
     );