always validate hostname from metadata

We introduced this metadata field in
#536 which landed in
0.9.1, which is old enough to rely on and not care for backups that
don't have this metadata field

lib/foreman_maintain/utils/backup.rb

@@ -183,24 +183,7 @@ def dumps_for_hybrid_db_setup(dbs_hash)
 
       def validate_hostname?
         # make sure that the system hostname is the same as the backup
-        hostname_from_metadata = metadata.fetch('hostname', nil)
-        if hostname_from_metadata
-          hostname_from_metadata == hostname
-        else
-          config_tarball = file_map[:config_files][:path]
-          tar_cmd = "tar zxf #{config_tarball} etc/httpd/conf/httpd.conf --to-stdout --occurrence=1"
-          status, httpd_config = execute_with_status(tar_cmd)
-
-          # Incremental backups sometimes don't include httpd.conf. Since a "base" backup
-          # is restored before an incremental, we can assume that the hostname is checked
-          # during the base backup restore
-          if status == 0
-            match = httpd_config.match(/\s*ServerName\s+"*([^ "]+)"*\s*$/)
-            match ? match[1] == hostname : false
-          else
-            true
-          end
-        end
+        metadata.fetch('hostname', nil) == hostname
       end
 
       def validate_interfaces

test/files/backups/katello_standard_pulpcore_database/metadata.yml

@@ -0,0 +1,22 @@
+---
+os_version: CentOS Stream 8
+plugin_list:
+- foreman-tasks-9.1.1
+- foreman_puppet-6.3.0
+- foreman_remote_execution-13.1.0
+- katello-4.13.0.pre.master
+proxy_features:
+- dynflow
+- logs
+- pulpcore
+- puppet
+- puppetca
+- script
+incremental: false
+online: false
+hostname: sat-6.example.com
+proxy_config:
+  dhcp: false
+  dhcp_interface: eth0
+  dns: false
+  dns_interface: eth0