Security Cases Alerts table fails with pagination on 100 Alerts

[EricDavisX]

Kibana version: 8.6.0-snapshot, kibana commit: 3f62042
Update: Bug was confirmed as still reproducible in 8.5.0 GA on cloud-prod .

Original install method (e.g. download page, yum, from source, etc.):
Tested on cloud-deploy to staging

Describe the bug:
If you browse to a security case that has 100 alerts attached and view the alerts table and change pagination to 100 the calls timeout and the ui shows strange grey bars for the 100 alert rows

Steps to reproduce:

1. create a security case
2. create one or more security rules and trigger 100 alerts from them
3. attach the alerts to the security case, and browse to the Alerts table
4. select '50' alerts pagination, this works. select 100 and the UI hangs, and repeated /internal/bsearch?compress=true calls are made

Expected behavior:
ui renders the 100 alerts

Screenshots (if relevant):

and if you click the arrows-expand icon while the UI is hung, it blows up, as seen:

Errors in browser console (if relevant):
the UI keeps calling /internal/besearch?compress=true with payload like the below:

example payload:
payload.txt

Any additional context:

• it works with 75 alerts attached to the case and viewing all of them, and is quite quick - so it doesn't 'feel' like purely a load problem with getting 100 alerts versus the sl;ightly smaller 75
• testing this with the env-bootstrap 'rac100' call is helpful, it creates all the rules and alerts, you just need to bulk enable them to create the alerts

[elasticmachine]

Pinging @elastic/response-ops (Team:ResponseOps)