tests/ostree.sync: tag with "reprovision"

There is a race condition for `ostree.sync` and `kdump.crash.nfs`
to bind port 2049, according to #4117 (comment),
add tag `reprovision` to force it to run serially now.

Author: HuijingHei

mantle/kola/tests/ostree/sync.go

@@ -78,7 +78,9 @@ func init() {
 		Name:        "ostree.sync",
 		Description: "Verify ostree can sync the filesystem with disconnected the NFS volume.",
 		Distros:     []string{"rhcos"},
-		Tags:        []string{"ostree", kola.SkipBaseChecksTag, kola.NeedsInternetTag},
+		// Tag to run serially to avoid NFS port conflicts.
+		// See https://github.com/coreos/coreos-assembler/issues/4117#issuecomment-3495048106
+		Tags:        []string{"ostree", kola.SkipBaseChecksTag, kola.NeedsInternetTag, "reprovision"},
 	})
 }