GnuTests.yml: Dedup setenforce 1

[oech3]

We don't need to setenforce 1 (and should not for performance?) before building.

[codspeed-hq]

CodSpeed Performance Report

Merging this PR will degrade performance by 3.06%

_{Comparing oech3:patch-9 (1c5a41f) with main (fe748f4)}

Summary

⚡ 2 improved benchmarks
❌ 1 regressed benchmark
✅ 279 untouched benchmarks
⏩ 38 skipped benchmarks¹

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Memory	du_deep_tree[(100, 3)]	159.2 KB	145.7 KB	+9.25%
❌	Memory	du_wide_tree[(5000, 500)]	1.2 MB	1.3 MB	-3.06%
⚡	Memory	dd_copy_partial	133.5 KB	129.1 KB	+3.37%

Footnotes

1. 38 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. ↩