(PE-14271) Have mock hosts return a hostname

Because BeakerAnswers sets hiera host parameters from Host#hostname, so
the method needs to exist in our mocks.

spec/beaker-pe/install/pe_utils_spec.rb

@@ -406,7 +406,7 @@ def slice_installer_options(host)
       expect(subject).to receive(:create_remote_file).with(
         master,
         '/tmp/pe.conf',
-        %r{\{.*"puppet_enterprise::puppet_master_host": "#{master}"}m
+        %r{\{.*"puppet_enterprise::puppet_master_host": "#{master.hostname}"}m
       )
       subject.generate_installer_conf_file_for(master, hosts, opts)
     end

spec/helpers.rb

@@ -83,6 +83,7 @@ def make_host name, host_hash
     host = make_opts.merge(host_hash)
 
     allow(host).to receive( :name ).and_return( name )
+    allow(host).to receive( :hostname ).and_return( "#{name}.test" )
     allow(host).to receive( :to_s ).and_return( name )
     allow(host).to receive( :exec ).and_return( generate_result( name, host_hash ) )
     host