[analyzer] Remove deprecated LintRule.categories

This field has been deprecated for a while and is no longer specified by any public lint rules.

Change-Id: Ic5ce4f29661f46d4bf9b3ed58f06d7c262090bbd
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/424220
Reviewed-by: Konstantin Shcheglov <[email protected]>
Commit-Queue: Brian Wilkerson <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

Author: parlough

pkg/analyzer/lib/src/lint/linter.dart

@@ -185,10 +185,6 @@ abstract class LintRule {
   /// Short description suitable for display in console output.
   final String description;
 
-  /// Deprecated field of lint groups (for example, 'style', 'errors', 'pub').
-  @Deprecated('Lint rule categories are no longer used.')
-  final Set<String> categories;
-
   /// Lint name.
   final String name;
 
@@ -197,8 +193,6 @@ abstract class LintRule {
 
   LintRule({
     required this.name,
-    @Deprecated('Lint rule categories are no longer used. Remove the argument.')
-    this.categories = const <String>{},
     required this.description,
     this.state = const State.stable(),
   });