Upload E2E logs on failure as GHA artifacts

[dereknola]

Proposed Changes

• Upload journald logs of each node as a GHA artifact on E2E test failure. An improvement over just dumping it into the output.
• Improved logic for forks when running the go docker tests in determining the "parent" branch that a PR comes from.

Types of Changes

Verification

See this run, where WASM and Private registry E2E tests were purposely failed. Note the available log artifacts
https://github.com/dereknola/k3s/actions/runs/12602264364

Testing

Its all testing

Linked Issues

#11532

User-Facing Change

Further Comments

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 39.44%. Comparing base (e64e2fc) to head (7d9560b).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #11514      +/-   ##
==========================================
- Coverage   43.85%   39.44%   -4.41%     
==========================================
  Files         181      164      -17     
  Lines       18809    18330     -479     
==========================================
- Hits         8249     7231    -1018     
- Misses       9351     9895     +544     
+ Partials     1209     1204       -5     

Flag	Coverage Δ
e2etests	35.81% <ø> (+0.01%)	⬆️
inttests	35.02% <ø> (+0.04%)	⬆️
unittests	?

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[VestigeJ]

Noice