DYN-5210: Fix column width in custom selection node when no entries.

[twastvedt]

Purpose

Issue	Fixed

This PR fixes DYN-5210. When the custom selection node's list is empty, the "Display" and "Value" headers would collapse to a minimum width. Now they stay in the same place.

Declarations

Check these if you believe they are true

• [x] The code base is in a better state after this PR
• [x] Is documented according to the standards
• [x] The level of testing this PR includes is appropriate
• [x] User facing strings, if any, are extracted into *.resx files
• [x] All tests pass using the self-service CI.
• [x] Snapshot of UI changes, if any.

Reviewers

@avidit

[twastvedt]

@avidit I just saw your note in Jira about preventing deletion of the last list item. I think that makes sense. I'll go ahead and do that and add it here.

[twastvedt]

OK, now it's ready @avidit!

[twastvedt]

@avidit what's the status of 2.16.1 - should I cherry pick this into there?

[QilongTang]

@twastvedt was it supposed to be part of 2.16.1? If yes, please specify early next time. 2.16.1 was released yesterday

[twastvedt]

nope. Ignore the above. Was not clear on release dates.