Disable use_sync_service_token_worker feature flag by default

Changelog: changed

config/feature_flags/development/use_sync_service_token_worker.yml

 ---
 name: use_sync_service_token_worker
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/135486
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/136078
 rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/431608
 milestone: '16.7'
 type: development
 group: group::cloud connector
-default_enabled: true
+default_enabled: false