Fixed users href path being incorrect

Does not remove the issue from the selected tab when it it de-selected, it instead gets purged when changing tab

Allows to use slash command /target_branch <target_branch_name> in merge requests notes and description.
Command allows to specify target branch for current merge request.

Proposed in #23619

Rename Build to Job

Replace "Builds" by "Jobs" and fix broken specs

Replace "Builds" by "Jobs"

Fix broken spinach test

Fix broken test

Remove `˙` at the beginning of the file

Fix broken spinach test

Fix broken tests

Changes after review

Group label link was pointing to group#issues rather than the projects issues. This fixes that by sending the correct subject to the link_to_label helper method.

Closes #27253

Ports changes from https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/642 back into CE

Upate test to match the new behavior

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

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`

Fixed delete labels not working

Review changes

Added test to replicate the bug, also added a couple of helpers that can be reused
on the testing suite to resize the browser window, these helpers are located on the
spec/support/mobile_helpers.rb

Fix linter error

Issue filter now appends a space & the test wasn't taking this into
account when checking the value