Without this parameter, every load of a Wiki page will load all the Wiki pages
in the repository for the sidebar. This is a significant performance penalty
that can significant slow the display of all Wiki pages.

Relates to #40101

This old migration used Rugged to find a commit, while Gitaly is the
prefered way now. By migrating this to Gitaly, Gitaly is now a required
running component for this migration.

Part of https://gitlab.com/gitlab-org/gitaly/issues/1106

After trying to remove the whole method in
8f69014af2902d8d53fe931268bec60f6858f160, this is a more gentle
approach to the method. :)

Prior to this change, new commit detection wasn't implemented in Gitaly,
this was done through: https://gitlab.com/gitlab-org/gitaly/merge_requests/779

As the new implemented got moved around a bit, the whole RevList class
got removed.

Part of https://gitlab.com/gitlab-org/gitaly/issues/1233

A process that spews a lot of output to stderr or stdout could stall out
due to the pipe buffer being full. As described in https://bugs.ruby-lang.org/issues/9082,
we can use the trick used in Ruby's capture3 function to read the pipes in separate
threads.

Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/6895

This partially reverts commit 64dfe2cb.

This reverts merge request !20339

Closes https://gitlab.com/gitlab-org/gitaly/issues/326

Prior to this change, most the commits counted were done through Gitaly.
This removes the last point where this wasn't the case.

This makes the `rugged_count_commits` method obsolete, with its tests.

Closes https://gitlab.com/gitlab-org/gitaly/issues/315

This prepares this code for migration to Gitaly.

This specific one isn't used on most machines, therefor low risk.

Closes https://gitlab.com/gitlab-org/gitaly/issues/944