android: Update source control tools reference

Repo URL is outdated and version control is no longer in existence.
Replace both in favour of Source Control Tools page which contains both existing tools
as well as some other useful ones like Gerrit, Android Code Search and more.

Signed-off-by: Aayush Gupta <aayushgupta219@gmail.com>
Change-Id: Iea66c6001cf8fde6717cb53d4cd5610f63d40043