[Eventing] - Collection drop which has is a associated eventing function should not fail rebalance

Till Cheshire Cat
Bucket deletion is not allowed during rebalance/failover, hence deleting a bucket caused a associated eventing function undeploy to go through fine(in most cases, unless rebalance had started post bucket delete and before undeploy started, a small windows but still possible I guess).

In CC
In CC we can drop collections during rebalance, this would cause the associated eventing functions to be undeployed during rebalance causing rebalance to fail with following errors.

Rebalance exited with reason {service_rebalance_failed,eventing,

{worker_died,

{'EXIT',<0.30539.58>,

{{badmatch,

{error,

{bad_nodes,eventing,prepare_rebalance,

[{'ns_1@172.23.98.195',

{error,

{unknown_error,

<<"Some apps are deploying or resuming on some or all Eventing nodes">>}}}]}}},

[{service_rebalancer,rebalance_worker,1,

[{file,"src/service_rebalancer.erl"},

{line,164}]},

{proc_lib,init_p,3,

[{file,"proc_lib.erl"},{line,234}]}]}}}}.

Rebalance Operation Id = 1bc902125845f74428f92a52879fc77c

Even though its not a bug per se, this would cause lot of issues in testing/customer use cases. I can possibly see every rebalance test we have in eventing failing during rebalance as CRUD on collections is a must in collections + eventing testing.

Should we undeploy post rebalance completion ?