Make teamcity ui settings readonly (#2608)

* teamcity: specify working github token in dsl

* teamcity: disable settings editing in UI

If VCS root doesn't have push permissions, push of settings changes
made in UI fail. After that synchronization with VCS is disabled in
order to not loose UI changes. With read-only UI all changes have to
be made in dsl.

.teamcity/settings.kts

@@ -68,6 +68,9 @@ project {
         }))
     }
     buildType(AggregatorBuild(tests))
+    params {
+        param("teamcity.ui.settings.readOnly", "true")
+    }
 }
 
 class AggregatorBuild(tests: Collection<BuildType>) : BuildType({