fix(12782): display actual error msg for failed mr creation

[gitdallas]

closes: https://issues.redhat.com/browse/RHOAIENG-12782

Description

give the real error message from k8s, this includes "[name] already exists"

How Has This Been Tested?

locally, kserve cluster, creating an MR (in MR settings) that has the same name as an existing MR. Run backend and frontend separately to see the changes in this PR.

Test Impact

none

Request review criteria:

Self checklist (all need to be checked):

• The developer has manually tested the changes and verified that the changes work
• Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• The developer has added tests or explained why testing cannot be added (unit or cypress tests for related changes)

If you have UI changes:

• Included any necessary screenshots or gifs if it was a UI change.

After the PR is posted & before it merges:

• The developer has tested their solution on a cluster by using the image produced by the PR to main

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.58%. Comparing base (537a427) to head (91c1e52).
Report is 38 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3444      +/-   ##
==========================================
- Coverage   85.95%   85.58%   -0.37%     
==========================================
  Files        1339     1344       +5     
  Lines       30357    30551     +194     
  Branches     8388     8470      +82     
==========================================
+ Hits        26093    26147      +54     
- Misses       4264     4404     +140     

see 38 files with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 537a427...91c1e52. Read the comment docs.

[manaswinidas]

/lgtm

Needed to run backend and frontend separately to see the changes in this PR... will update the PR description. [edit] updated the PR description "How has this been tested?" section.

[mturley]

LGTM, thanks @gitdallas

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: manaswinidas, mturley

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [mturley]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment