Fix errorcode 500 on slash commands

Closes #26013

See merge request !8285

Fix format of Slack when result is nil

Closes #25954

See merge request !8248

Slack docs [ci skip]

See merge request !8269

[ci skip] Fix wrong release date for 8.15.0 on CHANGELOG

See merge request !8294

Adds background color for disabled state to merge when succeeds dropdown

Closes #25905

See merge request !8222

Resolve "Titles are bigger than usual"

Closes #25906

See merge request !8235

Fix state_event parameter to reopen an issue

Closes #25958

See merge request !8246

Fix dropdown content non appearing in MR view

Closes #25961

See merge request !8255

Stops GFM special characters interfering with markdown tags

See merge request !8265

Add more images to issue creation from unresolved discussions

See merge request !8279

Fix code that selects latest pipelines

Closes #25993 and #26031

See merge request !8286

Improve autodeploy docs

See merge request !8242

Fix Mattermost command creation by specifying username

See merge request !8257

Don't render inline math when dollar signs are inside markup

See merge request !8259

Do not show retried builds in pipeline stage dropdown

Closes #25980

See merge request !8260

Fix viewing "build failed" TODOs

Closes #25979

See merge request !8262

[ci skip]

Cache last commit id for path

See merge request !8098

Fix lookup of project by unknown ref when caching is enabled

Closes #24224

See merge request !7988

Whitelist next project names: notes, services

See merge request !8239

* Also is not a good idea to use File.open without closing the file
  handler. We should use it with a block or close it explicitly.

Exclude non existent repository storages.

See merge request !8244

fixed minor animation glitch in mini pipeline graph animation

See merge request !8243

Resolve "KaTeX fonts 404 on gitlab.com"

Closes #25896

See merge request !8228

Update Bitbucket callback URL documentation

Closes #25950

See merge request !8241

Resolve "Remove Builds tab from Merge Requests and Commits"

Closes #23638

See merge request !7763

Auto deploy

Closes #23580

See merge request !8135

Filter protocol-relative URLs in ExternalLinkFilter. Fixes issue #22742.

Closes #22742

See merge request !6635

Improve Build Log scrolling experience

Closes #19620

See merge request !7895

fixes left align issue for long system notes

Closes #25368 and #25833

See merge request !7982

Change code font size to 12px

See merge request !8157

Merge branch '25897-textarea-stops-accepting-space-and-return-characters-with-no-warning' into 'master'

Fix space, return and tab blocks on textareas

Closes #25897

See merge request !8218

Remove unused services from the database

Closes #25727

See merge request !8225

Whitelist more project names

See merge request !8227

Put back progress bar CSS

Closes #25938

See merge request !8237

Use Grape's new Route methods

See merge request !8223