Remove incorrect test_cpu_seconds_can_detect_multiprocess

[eivindjahren]

Issue
Resolves #10009

The test fails very often even with rerun=10, so it is simply incorrect and we should just remove it.

• PR title captures the intent of the changes, and is fitting for release notes.
• Added appropriate release note label
• Commit history is consistent and clean, in line with the contribution guidelines.
• Make sure unit tests pass locally after every commit (git rebase -i main --exec 'just rapid-tests')

When applicable

• When there are user facing changes: Updated documentation
• New behavior or changes to existing untested code: Ensured that unit tests are added (See Ground Rules).
• Large PR: Prepare changes in small commits for more convenient review
• Bug fix: Add regression test for the bug
• Bug fix: Create Backport PR to latest release

[berland]

Has flakyness been observed since we tuned this function the last time (and we also skip it on Mac)

[eivindjahren]

Has flakyness been observed since we tuned this function the last time (and we also skip it on Mac)

Last failure was here: https://github.com/equinor/ert/actions/runs/13671775651/job/38223383104 which was the day after the skip on mac change.

[codspeed-hq]

CodSpeed Performance Report

Merging #10233 will not alter performance

_{Comparing eivindjahren:remove_non_working_test (72299c8) with main (07111bb)}

Summary

✅ 25 untouched benchmarks

[berland]

✂️