[MM-69126] Fix custom emoji upload size and GIF frame limits (#36984) (#37088)

* [MM-69126] Fix custom emoji upload size and GIF frame limits

* Assert 413 status and error ID in oversized emoji test

* Raise max emoji GIF frames to 70

* Enforce emoji GIF frame limit on the direct-write path

server/i18n/en.json

@@ -2056,6 +2056,10 @@
     "id": "api.emoji.upload.seek.app_error",
     "translation": "Unable to seek to file start."
   },
+  {
+    "id": "api.emoji.upload.too_many_frames.app_error",
+    "translation": "Unable to create emoji. Animated GIF must have at most {{.MaxFrames}} frames."
+  },
   {
     "id": "api.error_get_first_admin_complete_setup",
     "translation": "Error trying to retrieve first admin complete setup from the store."