Filter popover position is incorrect when its selector moves

[lucasfcosta]

Kibana version: 7.16 (SHA c5228354e5fdaf66f8466693f23f3d46d5632b88)

Elasticsearch version: 7.16

Server OS version: MacOS Big Sur 11.6

Browser version: Google Chrome Version 95.0.4638.69 (Official Build) (x86_64)

Browser OS version: MacOS Big Sur 11.6

Original install method (e.g. download page, yum, from source, etc.): I'm running Kibana from source, and connecting it to a 7.16-snapshot container from docker.elastic.co.

Describe the bug: When you open a filter popover, its position doesn't remain relative to the select it popped over from.

As you can see in the GIF below, as the popover source moves (because the modal is resized) the popover itself position changes incorrectly.

Steps to reproduce:

1. Within Observability > Cases, create two or more cases using different reporters for each
2. Access Uptime > Analyze Data (Exploratory View)
3. Create a visualisation and click "Add to case"
4. Change the "reporter" filter multiple times so that the modal also changes size and you'll see the popover position becomes incorrect.

Expected behavior: The popover position should remain where the selector which triggered it is.

Screenshots (if relevant):

Errors in browser console (if relevant): None.

Provide logs and/or server output (if relevant): None.

Any additional context: This was found as I was testing elastic/uptime#322.

@shahzad31 mentioned this issue should not receive the Team:uptime label as this is not the team that maintains this component, so I'd appreciate further guidance on proper labeling here.

[elasticmachine]

Pinging @elastic/uptime (Team:uptime)

[shahzad31]

This component isn't owned by us.

[shahzad31]

Tagging security solution, i think they work on cases plugin,

[elasticmachine]

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