Remove approval_rules_drawer feature flag

app/controllers/projects/settings/branch_rules_controller.rb

...ontrollers/projects/settings/merge_requests_controller.rb

config/feature_flags/beta/approval_rules_drawer.yml

doc/user/project/merge_requests/approvals/rules.md

...s/javascripts/approvals/components/approval_rules_app.vue

...vascripts/approvals/components/rule_modal/create_rule.vue

...ets/javascripts/approvals/components/rules/empty_rule.vue

...ts/security_configuration/unconfigured_security_rules.vue

ee/app/assets/javascripts/approvals/stores/index.js

...s/javascripts/approvals/stores/modules/mr_edit/actions.js

...ipts/approvals/stores/modules/project_settings/actions.js

...ollers/ee/projects/merge_requests/creations_controller.rb

ee/app/controllers/ee/projects/merge_requests_controller.rb

...rojects/settings/merge_request_approvals_settings_spec.rb

.../frontend/approvals/components/approval_rules_app_spec.js

...ntend/approvals/components/rule_modal/create_rule_spec.js

...ecurity_configuration/unconfigured_security_rules_spec.js

...approvals/stores/modules/project_settings/actions_spec.js

locale/gitlab.pot