Request timeout const name correction (#2743)

* request timeout value correction

* request timeout constant name change

---------

Co-authored-by: Lahiru Maramba <llahiru@gmail.com>

src/messaging/batch-request-internal.ts

@@ -20,7 +20,7 @@ import {
 import { FirebaseAppError, AppErrorCodes } from '../utils/error';
 
 const PART_BOUNDARY = '__END_OF_PART__';
-const TEN_SECONDS_IN_MILLIS = 15000;
+const FIFTEEN_SECONDS_IN_MILLIS = 15000;
 
 /**
  * Represents a request that can be sent as part of an HTTP batch request.
@@ -72,7 +72,7 @@ export class BatchRequestClient {
       url: this.batchUrl,
       data: this.getMultipartPayload(requests),
       headers: Object.assign({}, this.commonHeaders, requestHeaders),
-      timeout: TEN_SECONDS_IN_MILLIS,
+      timeout: FIFTEEN_SECONDS_IN_MILLIS,
     };
     return this.httpClient.send(request).then((response) => {
       if (!response.multipart) {