This index is added on `(target_project_id, iid)` and has a `WHERE state
= 'opened'` condition. Using this index we can drastically improve the
performance of the query used to count the total number of merge
requests in a group. Without this index the query would eventually
perform the following:

    ->  Index Scan using index_merge_requests_on_target_project_id_and_iid on merge_requests  (cost=0.43..4.89 rows=7 width=4) (actual time=0.058..0.353 rows=6 loops=228)
          Index Cond: (target_project_id = projects.id)
          Filter: ((state)::text = 'opened'::text)
          Rows Removed by Filter: 141
          Buffers: shared hit=34351 dirtied=1

Out of the ~180 milliseconds the entire query would take, around 170
milliseconds was spent in just this segment. With the index in place,
the above segment is turned into the following:

    ->  Index Only Scan using yorick_test on merge_requests  (cost=0.42..0.55 rows=7 width=4) (actual time=0.004..0.010 rows=6 loops=228)
          Index Cond: (target_project_id = projects.id)
          Heap Fetches: 419
          Buffers: shared hit=1381

The index also reduces the total query time to roughly 10 milliseconds.

GroupProjectsFinder#collection_with_user would run the following code:

    if group.users.include?(current_user)

When running this code for multiple groups this would result in one
query being executed for every group.

This commit simple removes the entire "if" statement with the code of
the "else" statement. This ensures both paths use the same code, and
removes the need for explicitly checking if a user is a member of the
group.

This reduces the number of queries necessary when displaying the
activity page of a group.

Fix fast admin counters not working when PostgreSQL has secondaries

Closes #46742

See merge request gitlab-org/gitlab-ce!19154

Use Gitaly's DeleteAllRepositories RPC during backup restore

Closes gitaly#1194

See merge request gitlab-org/gitlab-ce!19086

Add username to terms message in git and API calls

Closes #46649

See merge request gitlab-org/gitlab-ce!19126

Update redis-namespace to 1.6.0

Closes #46846

See merge request gitlab-org/gitlab-ce!19166

Persist and use truncated note diffs instead requesting Gitaly in a N+1 manner on MR page

Closes #45190

See merge request gitlab-org/gitlab-ce!18991

Don't pass the repository path to Gitlab Shell

See merge request gitlab-org/gitlab-ce!19011

Fix failing static-analysis pipeline

Closes #46859

See merge request gitlab-org/gitlab-ce!19174

Add docs for frontend accessibility

See merge request gitlab-org/gitlab-ce!17624

Update Frontend documentation regarding Vue and Icons/Illustrations

See merge request gitlab-org/gitlab-ce!18995

This commit does a number of things:

1. Reduces the number of queries needed by perform a single query to get all
the tuples for the relevant rows.

2. Uses a transaction to query the tuple counts to ensure that the data
is retrieved from the primary.

Closes #46742

Backport changes of gitlab-ee!5852

See merge request gitlab-org/gitlab-ce!19145

Fix encoding of branch names on compare and new merge request page

Closes #46627

See merge request gitlab-org/gitlab-ce!19143

Upgrade to Bootstrap 4

Closes #45185 and #46710

See merge request gitlab-org/gitlab-ce!18232

Merge branch '46740-projectmilestones-setting-start_date-via-the-api-requires-a-second-parameter' into 'master'

Resolve "ProjectMilestones: Setting start_date via the API requires a second parameter"

Closes #46740

See merge request gitlab-org/gitlab-ce!19133

Authentiq gem update

See merge request gitlab-org/gitlab-ce!19137

Remove Gemnasium badge from project's README.md

Closes #45404

See merge request gitlab-org/gitlab-ce!19136

Remove dead link to Google Drive

See merge request gitlab-org/gitlab-ce!19139

Bring CE-EE parity to app/services/projects/destroy_service.rb

See merge request gitlab-org/gitlab-ce!19111

Resolve "gitlab 10.8 assumes that installation is a git working copy."

Closes #46600

See merge request gitlab-org/gitlab-ce!19125

Init documentation for embedded snippets

See merge request gitlab-org/gitlab-ce!19120

Resolve "Typo on the empty Pipelines page"

Closes #46768

See merge request gitlab-org/gitlab-ce!19140

Resolve "Show CI pipeline status in Web IDE"

Closes #44579

See merge request gitlab-org/gitlab-ce!19048