mkosi: Fix installation conditions for rpmautospec-rpm-macros

rpmautospec-rpm-macros is only in EPEL 9 so let's gate it properly
on that by splitting up the epel packages config file into two.

erofs-utils is in EPEL 9 and in CentOS Stream 10.

mkosi/mkosi.images/build/mkosi.conf.d/centos/mkosi.conf.d/erofs-utils.conf

@@ -0,0 +1,11 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+
+[TriggerMatch]
+Repositories=epel
+Release=9
+
+[TriggerMatch]
+Release=10
+
+[Content]
+Packages=erofs-utils

mkosi/mkosi.images/build/mkosi.conf.d/centos/mkosi.conf.d/rpmautospec-rpm-macros.conf

@@ -2,8 +2,7 @@
 
 [Match]
 Repositories=epel
+Release=9
 
 [Content]
-Packages=
-        erofs-utils
-        rpmautospec-rpm-macros
+Packages=rpmautospec-rpm-macros