github: fix a mergify rule that was invalid

When converting the mergify yaml to match the new matrix rules in
github workflow yaml, I added `build-nightly-server (opensuse, amd64)`
but that's not a valid rule. Remove them.

Signed-off-by: John Mulligan <[email protected]>

Author: phlogistonjohn

.github/mergify.yml

@@ -22,7 +22,6 @@ queue_rules:
       - check-success=build-ad-server (opensuse, amd64)
       - check-success=build-nightly-server (centos, amd64)
       - check-success=build-nightly-server (fedora, amd64)
-      - check-success=build-nightly-server (opensuse, amd64)
       - check-success=build-nightly-ad-server (fedora, amd64)
       - check-success=build-client (centos, amd64)
       - check-success=build-client (fedora, amd64)
@@ -56,7 +55,6 @@ pull_request_rules:
       - check-success=build-ad-server (opensuse, amd64)
       - check-success=build-nightly-server (centos, amd64)
       - check-success=build-nightly-server (fedora, amd64)
-      - check-success=build-nightly-server (opensuse, amd64)
       - check-success=build-nightly-ad-server (fedora, amd64)
       - check-success=build-client (centos, amd64)
       - check-success=build-client (fedora, amd64)