Update the build badge links in README and delete config files that are no
longer used.

Change-Id: I72957a4d7946484f8a7dc1f71e5f41c8cb78f2f6
ORIGINAL_AUTHOR=Thai Duong <thaidn@google.com>
GitOrigin-RevId: 9461d12fa486b3ecfc5ca50b545d693c59d0982b