do not push new users the gmail-oauth2 way

src/main/java/org/thoughtcrime/securesms/RegistrationActivity.java

@@ -424,6 +424,16 @@ protected Void doInBackground(Void... voids) {
             // and should be whitelisted by the supported oauth2 services
             String redirectUrl = "chat.delta:/"+BuildConfig.APPLICATION_ID+"/auth";
             oauth2url = dcContext.getOauth2Url(email, redirectUrl);
+
+            // remove gmail oauth2
+            //
+            // when we decide to remove gmail-oauth2 from core, this can be removed.
+            // in between, allowing renewal may be advantageous for existing users, allowing smooth updates.
+            if (oauth2url.startsWith("https://accounts.google.com/")) {
+              oauth2url = null;
+            }
+            // /remove gmail oauth2
+
             return null;
         }