Merge branch 'ph/defaultMrActivityFilters' into 'master'

Default enable mr_activity_filters flag

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/126998



Merged-by: Natalia Tepluhina <ntepluhina@gitlab.com>
Approved-by: Natalia Tepluhina <ntepluhina@gitlab.com>
Co-authored-by: Phil Hughes <me@iamphill.com>

config/feature_flags/development/mr_activity_filters.yml

 ---
 name: mr_activity_filters
 introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/115383
-rollout_issue_url:
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/412432
 milestone: '15.11'
 type: development
 group: group::code review
-default_enabled: false
+default_enabled: true