Default-enable :fetch_remote_params feature flag

The :fetch_remote_params feature flag has been rolled out into
production on June 18th without any observed issues. Let's
default-enable it.

Changelog: changed

config/feature_flags/development/fetch_remote_params.yml

@@ -5,4 +5,4 @@ rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/325528
 milestone: '13.12'
 type: development
 group: group::gitaly
-default_enabled: false
+default_enabled: true