Use guard clause in Helm::InstallCommand

lib/gitlab/kubernetes/helm/install_command.rb

@@ -43,7 +43,8 @@ module Gitlab
         end
 
         def optional_tls_flags
-          if files.key?(:'ca.pem')
+          return unless files.key?(:'ca.pem')
+
           " --tls" \
             " --tls-ca-cert #{files_dir}/ca.pem" \
             " --tls-cert #{files_dir}/cert.pem" \
@@ -52,5 +53,4 @@ module Gitlab
       end
     end
   end
-  end
 end