Disable unused tags count cache for Projects, Builds and Runners

+ remove complete leftover when Issues were tagged using acts_as_taggable

app/models/issue.rb

@@ -15,8 +15,6 @@ class Issue < ActiveRecord::Base
   DueThisWeek   = DueDateStruct.new('Due This Week', 'week').freeze
   DueThisMonth  = DueDateStruct.new('Due This Month', 'month').freeze
 
-  ActsAsTaggableOn.strict_case_match = true
-
   belongs_to :project
   belongs_to :moved_to, class_name: 'Issue'
 

app/models/project.rb

@@ -70,8 +70,7 @@ class Project < ActiveRecord::Base
 
   after_validation :check_pending_delete
 
-  ActsAsTaggableOn.strict_case_match = true
-  acts_as_taggable_on :tags
+  acts_as_taggable
 
   attr_accessor :new_default_branch
   attr_accessor :old_path_with_namespace

changelogs/unreleased/27989-disable-counting-tags.yml

+---
+title: Disable unused tags count cache for Projects, Builds and Runners
+merge_request:
+author:

config/initializers/acts_as_taggable.rb

+ActsAsTaggableOn.strict_case_match = true
+
+# tags_counter enables caching count of tags which results in an update whenever a tag is added or removed
+# since the count is not used anywhere its better performance wise to disable this cache
+ActsAsTaggableOn.tags_counter = false