Add type for pipeline stages resolver

This completes the elimination of todos for Graphql/ResolverType,
which is now a fully-enabled Rubocop rule.

.rubocop.yml

@@ -368,6 +368,8 @@ Cop/SidekiqOptionsQueue:
 
 Graphql/ResolverType:
   Enabled: true
+  Exclude:
+    - 'app/graphql/resolvers/base_resolver.rb'
   Include:
     - 'app/graphql/resolvers/**/*'
     - 'ee/app/graphql/resolvers/**/*'

.rubocop_manual_todo.yml

@@ -32,13 +32,6 @@ Graphql/IDType:
     - 'app/graphql/resolvers/error_tracking/sentry_error_stack_trace_resolver.rb'
     - 'app/graphql/resolvers/user_merge_requests_resolver.rb'
 
-Graphql/ResolverType:
-  Exclude:
-    - 'app/graphql/resolvers/base_resolver.rb'
-    - 'app/graphql/resolvers/ci/pipeline_stages_resolver.rb'
-    - 'app/graphql/resolvers/users/group_count_resolver.rb'
-    - 'ee/app/graphql/resolvers/vulnerabilities_base_resolver.rb'
-
 Gitlab/PolicyRuleBoolean:
   Exclude:
     - 'ee/app/policies/ee/identity_provider_policy.rb'

app/graphql/resolvers/ci/pipeline_stages_resolver.rb

@@ -5,6 +5,9 @@ module Resolvers
     class PipelineStagesResolver < BaseResolver
       include LooksAhead
 
+      type Types::Ci::StageType.connection_type, null: true
+      extras [:lookahead]
+
       alias_method :pipeline, :object
 
       def resolve_with_lookahead

ee/app/graphql/resolvers/vulnerabilities_base_resolver.rb

@@ -5,6 +5,7 @@
 # to finding the object to get vulnerabilities from so that developers writing
 # new resolvers don't have to repeat it.
 
+# rubocop: disable Graphql/ResolverType
 module Resolvers
   class VulnerabilitiesBaseResolver < BaseResolver
     include Gitlab::Utils::StrongMemoize