build-gnu.sh: Remove 2 not working sed hacks for tr

[oech3]

Closes #9469

[codspeed]

CodSpeed Performance Report

Merging #9476 will not alter performance

_{Comparing oech3:no-sed-tr (d7dfafc) with main (8d74025)¹}

Summary

✅ 126 untouched
⏩ 6 skipped²

Footnotes

1. No successful run was found on main (876ac06) during the generation of this report, so 8d74025 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

2. 6 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/tail/overlay-headers (passes in this run but fails in the 'main' branch)

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/tail/overlay-headers (fails in this run but passes in the 'main' branch)

[cakebaker]

Thanks!