CI: disable RST for now

Some tests fail or crash and block the whole run, so remove RST from the
base set.

Signed-off-by: David Sterba <dsterba@suse.com>

Author: kdave

.github/workflows/ci-kvm.yml

@@ -69,7 +69,6 @@ jobs:
           - '-o compress=zstd'
         mkfs:
           - ''
-          - '-O rst'
       # Let all tests continue even if some ends early
       fail-fast: false
     runs-on: [self-hosted, Linux, X64]