rpm: disable ceph for suse 15

there was an incompatible change in ceph in SUSE 15.1, so we disable
building ceph plugins there. You can just upgrade to Bareos 18.2 or
newer if you need these plugins.

platforms/packaging/bareos.spec

@@ -91,7 +91,7 @@ BuildRequires: libtirpc-devel
 %define droplet 1
 %endif
 
-%if 0%{?sle_version} >= 120000
+%if 0%{?sle_version} >= 120000 && 0%{?sle_version} < 150000
 %define ceph 1
 %endif