Revert "Fix arrow function detection in TypeScript/JavaScript outline (#38411)" (#38982)

This reverts commit 1bbf98aea6.

We found that #38411 caused problems where anonymous functions are
included too many times in the outline. We'd like to figure out a better
fix before shipping this to stable.

Fixes #38956

Release Notes:

- (preview only) revert changes to outline view

crates/languages/src/javascript/outline.scm

@@ -116,26 +116,4 @@
     )
 ) @item
 
-; Arrow functions in variable declarations (anywhere in the tree, including nested in functions)
-(lexical_declaration
-    ["let" "const"] @context
-    (variable_declarator
-        name: (_) @name
-        value: (arrow_function)) @item)
-
-; Async arrow functions in variable declarations
-(lexical_declaration
-    ["let" "const"] @context
-    (variable_declarator
-        name: (_) @name
-        value: (arrow_function
-            "async" @context)) @item)
-
-; Named function expressions in variable declarations
-(lexical_declaration
-    ["let" "const"] @context
-    (variable_declarator
-        name: (_) @name
-        value: (function_expression)) @item)
-
 (comment) @annotation