Bugfix/slack rate limiting (#4386)

* use slack's built in rate limit handler for the bot

* WIP

* fix the slack rate limit handler

* change default to 8

* cleanup

* try catch int conversion just in case

* linearize this logic better

* code review comments

---------

Co-authored-by: Richard Kuo (Onyx) <rkuo@onyx.app>

backend/onyx/redis/redis_pool.py

@@ -125,6 +125,7 @@ class TenantRedis(redis.Redis):
             "hset",
             "hdel",
             "ttl",
+            "pttl",
         ]  # Regular methods that need simple prefixing
 
         if item == "scan_iter" or item == "sscan_iter":