Merge branch 'sh-disable-parallel-matrix-feature-flag' into 'master'

Disable parallel matrix feature flag

See merge request gitlab-org/gitlab!37501

lib/gitlab/ci/features.rb

@@ -67,7 +67,7 @@ module Gitlab
       end
       def self.parallel_matrix_enabled?
-        ::Feature.enabled?(:ci_parallel_matrix_enabled, default_enabled: true)
+        ::Feature.enabled?(:ci_parallel_matrix_enabled)
       end
       def self.bulk_insert_on_create?(project)