Fix incorrect context name being created when using new tanzu platform endpoints

[anujc25]

What this PR does / why we need it

Fix incorrect context name being created when using new endpoints

Which issue(s) this PR fixes

Fixes #

Describe testing done for PR

Before this change:

$ tz login --staging --endpoint https://platform-dev.tanzu.broadcom.com

$ tz context list
  NAME                                      ISACTIVE  TYPE   PROJECT  SPACE
  tpsm-5a2f0150                             false     tanzu

After this change:

$ tz login --staging --endpoint https://platform-dev.tanzu.broadcom.com

$ tz context list
  NAME                                      ISACTIVE  TYPE   PROJECT  SPACE
  Falcons-staging-5a2f0150                  true      tanzu

Release note

Fix incorrect context name being created when using new tanzu platform endpoints

Additional information

Special notes for your reviewer

[marckhouzam]

I actually hit this problem yesterday while debugging and it was pretty annoying (and wrong).
Thanks for fixing!

In the PR description did you mean to refer to #801 instead of #808 (which is the current PR 😄 )

[vuil]

Thanks for the fix and updating the tests to clarify the behavior.
Just a small nit on the comments.