MB-46647: Set appropriate language_compatibility on /function endpoint

Change-Id: I039b52d3d4956858b26f1301b1e0c19f3ecb52ae
Reviewed-on: http://review.couchbase.org/c/eventing/+/154759
Reviewed-by: Jeelan Basha Poola <jeelan.poola@couchbase.com>
Reviewed-by: CI Bot
Tested-by: Vinayaka Kamath <vinayaka.kamath@couchbase.com>
(cherry picked from commit 2d01166)
Reviewed-on: http://review.couchbase.org/c/eventing/+/155909
Well-Formed: Restriction Checker
Tested-by: <abhishek.jindal@couchbase.com>

service_manager/http_handlers.go

@@ -3214,7 +3214,7 @@ func (m *ServiceMgr) functionsHandler(w http.ResponseWriter, r *http.Request) {
 			}
 
 			if _, ok := app.Settings["language_compatibility"]; !ok {
-				app.Settings["language_compatibility"] = common.LanguageCompatibility[len(common.LanguageCompatibility)-1]
+				app.Settings["language_compatibility"] = common.LanguageCompatibility[0]
 			}
 
 			runtimeInfo := m.savePrimaryStore(&app)