Remove `depend_on_persistent_pipeline_ref` feature flag

Closes #14863

See merge request gitlab-org/gitlab!18185

Allow config Sidekiq worker memory limit in ENV

See merge request gitlab-org/gitlab!18071

Make IS_GITLAB_EE consistent

See merge request gitlab-org/gitlab!18442

Currently:
1. If `IS_GITLAB_EE=` is used, it fails to generate Webpack
   as it cannot be parsed as JSON,
2. If `IS_GITLAB_EE=1` is used, it fails on GitLab CE,
3. If `IS_GITLAB_EE=0` it does work correctly, and disables EE,
4. If `IS_GITLAB_EE=1` is used on GitLab EE it effectively required
   to run on EE changes.

This changes to:

Make `IS_GITLAB_EE=` to donate the intent to disable or enable EE
sources, instead of requiring it, and makes the check consitent
in behaviour.

Bump GITLAB_ELASTICSEARCH_INDEXER_VERSION=v1.4.0

Closes #33255 and gitlab-elasticsearch-indexer#39

See merge request gitlab-org/gitlab!18558

Enable frozen string for spec/tasks

See merge request gitlab-org/gitlab!18552

Edit new configuration settings documentation

See merge request gitlab-org/gitlab!18557

Remove ActionType constants from epic tree frontend

See merge request gitlab-org/gitlab!17971

This commit removes the FF as it's deemed stable

Which fixes https://gitlab.com/gitlab-org/gitlab/issues/33255 and also
includes
https://gitlab.com/gitlab-org/gitlab-elasticsearch-indexer/merge_requests/39

Add more details on how to use Docker-based Gitlab with Docker-based PlantUML

See merge request gitlab-org/gitlab!18204

The MR also fixes the relative path to the PlantUML service

Fix metrics chart embed tooltip spacing

Closes #34063

See merge request gitlab-org/gitlab!18543

Operator can see all projects using an instance level cluster

See merge request gitlab-org/gitlab!18173

Refactor of appearance/customization docs

Closes #31189

See merge request gitlab-org/gitlab!18049

Move most information regarding the appearance section
to /user/admin_area, and redirect from /customization.
Updates screenshots, information, process, etc.

Fixed cert-manager retry logic to apply correct exit code

Closes #34065

See merge request gitlab-org/gitlab!18545

Partially addresses:

https://gitlab.com/gitlab-org/gitlab/issues/27703

Enable frozen string for spec/uploaders

See merge request gitlab-org/gitlab!18547

Partially addresses:

https://gitlab.com/gitlab-org/gitlab/issues/27703

Update Auto DevOps quickstart

Closes #33075

See merge request gitlab-org/gitlab!18356

Update guide to show new base domain loc, update images

Instructions to set your Geo Node Name

Closes #11501

See merge request gitlab-org/gitlab!18463

Use PlantUML intregration in PlantUML docs

See merge request gitlab-org/gitlab!18550

Productivity Analytics: Move daterange component to shared space

See merge request gitlab-org/gitlab!18383

- Refactor daterange component

Change Gitaly recommendations for 25k and 50k architectures in the docs

See merge request gitlab-org/gitlab!18531

EKS Cluster form static fields and security groups dropdown

See merge request gitlab-org/gitlab!17762

- Cluster name
- Environment scope
- Kubernetes version

Add end-to-end test to delete board via the graphical user interface

Closes gitlab-org/quality/testcases#226

See merge request gitlab-org/gitlab!18522

Clarify the usage of sentence case in headings

See merge request gitlab-org/gitlab!18535