Discover's "Toggle to Remove Column" in document's table view doesn't remove the column

[bczifra]

Kibana version: 7.12.0

Elasticsearch version: N/A

Server OS version: N/A

Browser version: Chrome Version 89.0.4389.114 (Official Build) (x86_64)

Browser OS version: N/A

Original install method (e.g. download page, yum, from source, etc.): Elastic Cloud

Describe the bug:
In Discover, Clicking the "Toggle column in table" option in a document's table view once will cause it to be shown as a column, as expected. Clicking it again, however, doesn't remove the column. Collapsing and then re-opening the document's table view, then clicking the option again will, correctly toggle (remove) the column.

This is likely related to #96694.

Steps to reproduce:

1. In Discover, expand a document
2. Click the "Toggle column in table" option in a document's table view
3. The field will be added as column, as expected.
4. Click the "Toggle column in table" option again (having left the document's table view expanded)
5. The column is not removed from the table, contrary to expectation.

Expected behavior:
Each time you click the option, it toggles between adding or removing the column.

Screenshots (if relevant):

[elasticmachine]

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