[YUNIKORN-2634] Remove deprecated usergroup resolution handling via the label

[ryankert01]

What is this PR for?

as discussed at YUNIKORN-2207.
should be done after 1.6 release.

What type of PR is it?

• - Bug Fix
• - Improvement
• - Feature
• - Documentation
• - Hot Fix
• - Refactoring

Todos

• - Task

What is the Jira issue?

https://issues.apache.org/jira/browse/YUNIKORN-2634

How should this be tested?

Screenshots (if appropriate)

Questions:

• - The licenses files need update.
• - There is breaking changes for older versions.
• - It needs documentation.

[wilfred-s]

LGTM +1

[chenyulin0719]

@wilfred-s , @craigcondit We didn't make deprecation announcement for yunikorn.apache.org/username in 1.6.0 . Should we postpone this change to next release?

• https://yunikorn.apache.org/release-announce/1.6.0/

[ryankert01]

Hi, @chenyulin0719. Maybe I should mark it as deprecated for now(rather than legacy)? (:

[chenyulin0719]

I think we haven't discussed whether to deprecate the legacy label yunikorn.apache.org/username.
For back compatibility, I prefer keep it as legacy. If we are going to deprecate the legacy label. I think a notification to user channel is required.

Need more feedback from other users/contributors.