Remove returns of promises within functions with callbacks (address DeprecationWarning) (#25603)

* [document-updater] Don't return promises within functions with callbacks

Remove the errors:
DeprecationWarning: Calling promisify on a function that returns a Promise is likely a mistake
https://cloudlogging.app.goo.gl/YHDhoarvLEw2w9rXA

* Remove some more unnecessary returns in functions with callbacks, for consistency

* Add `sendCanaryAppliedOp` to excluded methods for promisification

GitOrigin-RevId: fa6d3e47c4e6561dc29d4c15e57c3289fc1f3dfa

services/document-updater/app/js/RealTimeRedisManager.js

@@ -49,7 +49,7 @@ const RealTimeRedisManager = {
       MAX_OPS_PER_ITERATION,
       -1
     )
-    return multi.exec(function (error, replys) {
+    multi.exec(function (error, replys) {
       if (error != null) {
         return callback(error)
       }
@@ -80,7 +80,7 @@ const RealTimeRedisManager = {
   },
 
   getUpdatesLength(docId, callback) {
-    return rclient.llen(Keys.pendingUpdates({ doc_id: docId }), callback)
+    rclient.llen(Keys.pendingUpdates({ doc_id: docId }), callback)
   },
 
   sendCanaryAppliedOp({ projectId, docId, op }) {
@@ -132,5 +132,5 @@ const RealTimeRedisManager = {
 
 module.exports = RealTimeRedisManager
 module.exports.promises = promisifyAll(RealTimeRedisManager, {
-  without: ['sendData'],
+  without: ['sendCanaryAppliedOp', 'sendData'],
 })