AMBARI-7902 Admin View: Provide identical cluster name validation in Manage. (ababiichuk)

ambari-admin/src/main/resources/ui/admin-web/app/views/leftNavbar.html

@@ -33,7 +33,8 @@
                   type="text"
                   name="newClusterName"
                   ng-required="true"
-                  ng-pattern="/^[a-zA-Z0-9]*$/"
+                  ng-pattern="/^\w*$/"
+                  ng-trim="false"
                   ng-model="editCluster.name"
                   class="form-control input-sm"
                   tooltip="Only alpha-numeric characters."