Enable ci_allow_failure_with_exit_codes feature flag

Set Enable ci_allow_failure_with_exit_codes feature flag to default to
true

changelogs/unreleased/ci-enable-allow-failure-exit-codes.yml

+---
+title: Control job status using exit codes
+merge_request: 51439
+author:
+type: added

config/feature_flags/development/ci_allow_failure_with_exit_codes.yml

@@ -5,4 +5,4 @@ rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/292024
 milestone: '13.7'
 type: development
 group: group::pipeline authoring
-default_enabled: false
+default_enabled: true

doc/ci/yaml/README.md

@@ -2278,10 +2278,10 @@ job3:
 #### `allow_failure:exit_codes`
 
 > - [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/273157) in GitLab 13.8.
-> - It's [deployed behind a feature flag](../../user/feature_flags.md), disabled by default.
-> - It's disabled on GitLab.com.
-> - It's not recommended for production use.
-> - To use it in GitLab self-managed instances, ask a GitLab administrator to [enable it](#enable-or-disable-allow_failureexit_codes). **(CORE ONLY)**
+> - It's [deployed behind a feature flag](../../user/feature_flags.md), enabled by default.
+> - It's enabled on GitLab.com.
+> - It's recommended for production use.
+> - For GitLab self-managed instances, GitLab administrators can opt to [disable it](#enable-or-disable-allow_failureexit_codes). **(CORE ONLY)**
 
 WARNING:
 This feature might not be available to you. Check the **version history** note above for details.
@@ -2310,21 +2310,21 @@ test_job_2:
 
 ##### Enable or disable `allow_failure:exit_codes` **(CORE ONLY)**
 
-`allow_failure:exit_codes` is under development and not ready for production use. It is
-deployed behind a feature flag that is **disabled by default**.
+`allow_failure:exit_codes` is under development but ready for production use. It is
+deployed behind a feature flag that is **enabled by default**.
 [GitLab administrators with access to the GitLab Rails console](../../administration/feature_flags.md)
-can enable it.
+can disable it.
 
-To enable it:
+To disable it:
 
 ```ruby
-Feature.enable(:ci_allow_failure_with_exit_codes)
+Feature.disable(:ci_allow_failure_with_exit_codes)
 ```
 
-To disable it:
+To enable it:
 
 ```ruby
-Feature.disable(:ci_allow_failure_with_exit_codes)
+Feature.enable(:ci_allow_failure_with_exit_codes)
 ```
 
 ### `when`

lib/gitlab/ci/features.rb

@@ -64,7 +64,7 @@ module Gitlab
       end
 
       def self.allow_failure_with_exit_codes_enabled?
-        ::Feature.enabled?(:ci_allow_failure_with_exit_codes)
+        ::Feature.enabled?(:ci_allow_failure_with_exit_codes, default_enabled: :yaml)
       end
 
       def self.rules_variables_enabled?(project)