GoogleCloudStorageBlobStore.deleteBlobsIgnoringIfNotExists() does
not correctly catch StorageException thrown by batch.submit().
In the case a snapshot is deleted through BlobStoreRepository.deleteSnapshot()
a storage exception is not caught (only IOException are) so the deletion is
interrupted and indices cannot be cleaned up. The storage exception bubbles
up to SnapshotService.deleteSnapshotFromRepository() but the listener that
removes the deletion from the cluster state is not executed, leaving the
deletion in the cluster state.
This bug has been reported in #46772 where batch.submit() threw an
exception in the test testIndicesDeletedFromRepository and following
tests failed because a snapshot deletion was running.
Relates #46772
add7148f3b