[Discover] No way to remove non-existent selected fields

[cchaos]

Kibana version: Master & at least 7.6

Describe the bug:
When adding fields to the doc table in Discover, then switching to an index pattern that doesn't have that field name, there is no UI to allow removing it.

Steps to reproduce:

1. Starting with kibana_sample_data_flights, go to Discover and add the field hour_of_day to the table
2. Switch index patterns to kibana_sample_data_ecommerce
3. See the doc table still has the column for hour_of_day but the field isn't available in the sidebar to be removed.

Screenshots (if relevant):

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)

[kertal]

I wouldn't label it a regression, just tried it out in 6.8, 7.1 , and you can remove the column:

The question here is, if it would make sense to automatically remove the field, if it's not available

[Bargs]

I think Caroline was referring to the fact that it disappeared from the sidebar. I dunno if that's a regression or not though.

[kertal]

Yes, but that’s not a regression, which does not mean it should not be fixed :) Matt Bargar <notifications@github.com> schrieb am Fr. 24. Jän. 2020 um 17:53:

…

I think Caroline was referring to the fact that it disappeared from the sidebar. I dunno if that's a regression or not though. — You are receiving this because you are on a team that was mentioned. Reply to this email directly, view it on GitHub <#54653?email_source=notifications&email_token=AADRH2434GXQQBWNGSHXTEDQ7MMH5A5CNFSM4KGI5JT2YY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEJ3M6NY#issuecomment-578211639>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AADRH22KI7Y6K54QC5KSII3Q7MMH5ANCNFSM4KGI5JTQ> .

[kertal]

closing this because it was fixed in #74336

[kertal]

no closing this for real!