repo: upgrade 2.49.3 -> 2.50.1

repo: upgrade 2.49.3 -> 2.50.1

Changelog:
===========
- gc: Introduce new command to remove old projects
- sync: Delete symlinks relative to client topdir
- Add smoke test for subcmd forall
- Remove gitc support from repo
- branches: Escape percent signs in branch names
- sync: Do not fail to sync a manifest with no projects
- Fix event log command event hierarchy.
- Make repo installation work without .git

Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>