No error message displayed to user when "Request Entity Too large" error on updating Index Pattern

[babadofar]

Kibana version:
7.10
Elasticsearch version:
7.10
Server OS version:
elastic Cloud
Describe the bug:
Trying to update a very large index pattern in Kibana to add more fields. This fails silently, the page Is refreshed and no error message is displayed. You could actually believe that it worked. But opening the inspector and viewing the network requests shows this error

{"statusCode":413,"error":"Request Entity Too Large","message":"Payload content length greater than maximum allowed: 1048576"}

Steps to reproduce:

1. Have lots of data with lots of fields
2. Try to add another field
   3.Try to update index pattern in Kibana

Expected behavior:
The index pattern should refresh
Screenshots (if relevant):

Errors in browser console (if relevant):
{"statusCode":413,"error":"Request Entity Too Large","message":"Payload content length greater than maximum allowed: 1048576"}
Provide logs and/or server output (if relevant):

Any additional context:

[elasticmachine]

Pinging @elastic/kibana-stack-management (Team:Stack Management)

[elasticmachine]

Pinging @elastic/kibana-app-services (Team:AppServices)

[mattkime]

Hello @babadofar - As of 7.11, Kibana is no longer saving the whole field list which means this problem is no longer possible. You're encouraged to upgrade, if possible.

Relevant changes - #82223