Add the 8-16-3 changelog entries to master

See merge request !8912

Cop for gem fetched from a git source

Closes #27311

See merge request !8856

Corrected docs href's

See merge request !8527

Fix disable storing of sensitive information when importing a new repo

Closes #23767

See merge request !8885

Fix notification when group set to watch

Closes #395

See merge request !8883

Remove new branch button for confidential issues

Closes #27479

See merge request !8894

Promote project labels to group labels

Closes #24021

See merge request !7242

Resolve "Document that auto deploy only works for public projects"

Closes #27474

See merge request !8897

Remove outdated text and link to up-to-date documentation

See merge request !8789

Update and pin the `jwt` gem to ~> 1.5.6

Closes #27488

See merge request !8900

Fixes #24021

Convert pipeline action icons to svg to have them propperly positioned

Closes #25910

See merge request !8766

Avoid repeated dashes in $CI_ENVIRONMENT_SLUG

Closes #26852

See merge request !8638

Fix inconsistent return type

Closes #27150

See merge request !8290

Refactor MergeRequest::BuildService

Closes #24795

See merge request !8462

Services changed to Integrations

See merge request !8686

Signed-off-by: Rémy Coutable <remy@rymai.me>

Remove flash warning from login page

See merge request !8864

Ensure rake is called within the correct bundle context

See merge request !8882

Expose pipelines API for commits and merge requests

See merge request !8837

add changelog entry

replace local variables `merge_request` with instance ones

modify `MergeRequests::BuildService` to fix failed tests

extract `assign_target_project` method

remove unnecessary instance variables

remove exclamation marks and rewrite conditionals to improve readability

extract `params_does_not_contain_branches?` method, rename `unprepared_merge_request` method to `uncreatable_merge_request`

replace instance variables `merge_request` and `error_messages` with getters and setters; divide `set_title_and_description` method on two separate ones

refactor `execute` method

return `set_title_and_description` method

rename `branches_selected?` method to `branches_present?` to make it more different from `branches_specified?`

fixes after discussion

renamed method branches_valid?

fix space

return assigning methods into `execute` method

simplify `find_target_branch` and `find_source_project` methods

fix spec `merge request issuable record that supports slash commands in its description and notes`

code fix for aesthetic & conventions

remove unused proc

Add project ID index to `project_authorizations` table to optimize queries

Closes #27443

See merge request !8890

Resolve "ba-resize memory leak"

Closes #26282

See merge request !8412

As described in #27443, the `project_authorizations` table is often used to retrieve
all team members of this project. This can lead to a number of slow queries impacting
load times. This MR adds an index for just `project_id`.

Closes #27443

Resets issue boards assignee dropdown

Closes #26514 and #26814

See merge request !8540

Move todos empty state icons

See merge request !7370

Fix build access policies when pipelines are public

See merge request !8711

Signed-off-by: Rémy Coutable <remy@rymai.me>

Fix 8.16.0 release date.

See merge request !8881