Drop pkg:js from "Web (Legacy)" docs section

Since it's not showing up deprecated.

Bug: https://github.com/dart-lang/sdk/issues/59716
Change-Id: I6d61a16a04571547036a3a1c04d744781d8ef2e7
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/403962
Auto-Submit: Kevin Moore <kevmoo@google.com>
Reviewed-by: Srujan Gaddam <srujzs@google.com>
Commit-Queue: Kevin Moore <kevmoo@google.com>

tools/write_dartdoc_options_file.py

@@ -43,13 +43,6 @@ def Main(argv):
             dart:html and similar Dart SDK libraries. It will support access to
             browser APIs from Dart code compiled to either JavaScript or
             WebAssembly.
-    'Web (Legacy)':
-      external:
-        - name: 'package:js'
-          url: https://pub.dev/documentation/js/latest/
-          docs: >-
-            Use this package when you want to call JavaScript APIs from Dart
-            code, or vice versa.
   linkToSource:
     root: '.'
     uriTemplate: 'https://github.com/dart-lang/sdk/blob/%s/sdk/%%f%%#L%%l%%'