unexpand: remove unnecessary condition

[cakebaker]

This PR removes an unnecessary condition I overlooked while reviewing #8815.

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/misc/tee (passes in this run but fails in the 'main' branch)

[codspeed-hq]

CodSpeed Performance Report

Merging #8822 will not alter performance

_{Comparing cakebaker:unexpand_remove_unnecessary_condition (658e0d8) with main (af27562)¹}

Summary

✅ 79 untouched
⏩ 73 skipped²

Footnotes

1. No successful run was found on main (5e076fe) during the generation of this report, so af27562 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

2. 73 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. ↩