ceph: fix object store healthcheck yaml

Reverting some of
https://github.com/rook/rook/commit/23f0ac7f9c7157383bc860b259c1964df46454c1
to re-use `bucket` for the healthcheck configuration.

Signed-off-by: Sébastien Han <seb@redhat.com>

pkg/apis/ceph.rook.io/v1/types.go

@@ -450,7 +450,7 @@ type ObjectStoreSpec struct {
 }
 
 type BucketHealthCheckSpec struct {
-	Bucket        HealthCheckSpec   `json:"rgw,omitempty"`
+	Bucket        HealthCheckSpec   `json:"bucket,omitempty"`
 	LivenessProbe *rookv1.ProbeSpec `json:"livenessProbe,omitempty"`
 }