fix(matrix): use absolute repository name

This patch uses the absolute repository name, making sure that
multi-registry configs, like cri-o uses on Fedora won't try to pull
things from quay or other registries.

apps/base/matrix/release.yaml

@@ -23,6 +23,8 @@ spec:
     remediation:
       retries: -1
   values:
+    image:
+      repository: docker.io/matrixdotorg/synapse
     # serverName: example.com
     # publicServerName: matrix.example.com
     signingkey: