ceph: osd remove --conf flag

Even legacy osds were still running with this flag. In my previous patch
I was trying to minimize the impact of the change and was afraid the
config file was holding important information but that appears not to be
true.

The only option in the config could have the keyring path, but it's
passed in the CLI startup line.

Closes: https://github.com/rook/rook/issues/4063
Signed-off-by: Sébastien Han <seb@redhat.com>

pkg/operator/ceph/cluster/osd/spec.go

@@ -181,7 +181,6 @@ func (c *Cluster) makeDeployment(osdProps osdProperties, osd OSDInfo) (*apps.Dep
 	defaultArgs := []string{
 		"--foreground",
 		"--id", osdID,
-		"--conf", osd.Config,
 		"--osd-data", osd.DataPath,
 		"--keyring", osd.KeyringPath,
 		"--cluster", osd.Cluster,