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.

# User-Facing Changes
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helps us keep track of breaking changes. -->
None

# Tests + Formatting
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crates/nu-command/tests/commands/join.rs

@@ -84,7 +84,7 @@ fn do_cases_where_result_is_same_between_join_types(join_type: &str) {
         (("[{a: 1}]", "[{a: 1 b: 1}]", "a"), "[[a, b]; [1, 1]]"),
     ] {
         let expr = format!("{} | join {} {} {} | to nuon", left, right, join_type, on);
-        let actual = nu!(cwd: ".", expr).out;
+        let actual = nu!(expr).out;
         assert_eq!(actual, expected);
 
         // Test again with streaming input (using `each` to convert the input into a ListStream)
@@ -93,7 +93,7 @@ fn do_cases_where_result_is_same_between_join_types(join_type: &str) {
             "{} | {} join {} {} {} | to nuon",
             left, to_list_stream, right, join_type, on
         );
-        let actual = nu!(cwd: ".", expr).out;
+        let actual = nu!(expr).out;
         assert_eq!(actual, expected);
     }
 }
@@ -199,7 +199,7 @@ fn do_cases_where_result_differs_between_join_types(join_type: &str) {
         for (join_type_, expected) in join_types {
             if join_type_ == join_type {
                 let expr = format!("{} | join {} {} {} | to nuon", left, right, join_type, on);
-                let actual = nu!(cwd: ".", expr).out;
+                let actual = nu!(expr).out;
                 assert_eq!(actual, expected);
 
                 // Test again with streaming input (using `each` to convert the input into a ListStream)
@@ -208,7 +208,7 @@ fn do_cases_where_result_differs_between_join_types(join_type: &str) {
                     "{} | {} join {} {} {} | to nuon",
                     left, to_list_stream, right, join_type, on
                 );
-                let actual = nu!(cwd: ".", expr).out;
+                let actual = nu!(expr).out;
                 assert_eq!(actual, expected);
             }
         }
@@ -339,7 +339,7 @@ fn do_cases_where_result_differs_between_join_types_with_different_join_keys(joi
         for (join_type_, expected) in join_types {
             if join_type_ == join_type {
                 let expr = format!("{} | join {} {} {} {} | to nuon", left, right, join_type, left_on, right_on);
-                let actual = nu!(cwd: ".", expr).out;
+                let actual = nu!(expr).out;
                 assert_eq!(actual, expected);
 
                 // Test again with streaming input (using `each` to convert the input into a ListStream)
@@ -348,7 +348,7 @@ fn do_cases_where_result_differs_between_join_types_with_different_join_keys(joi
                     "{} | {} join {} {} {} {} | to nuon",
                     left, to_list_stream, right, join_type, left_on, right_on
                 );
-                let actual = nu!(cwd: ".", expr).out;
+                let actual = nu!(expr).out;
                 assert_eq!(actual, expected);
             }
         }
@@ -366,7 +366,7 @@ fn test_alternative_table_syntax() {
         (("[[a]; [1]]", "[[a]; [1]]", "a"), "[[a]; [1]]"),
     ] {
         let expr = format!("{} | join {} {} {} | to nuon", left, right, join_type, on);
-        let actual = nu!(cwd: ".", &expr).out;
+        let actual = nu!(&expr).out;
         assert_eq!(actual, expected, "Expression was {}", &expr);
     }
 }