Revert "fuzzing.yml: Bump GNU coreutils to 9.11"

[sylvestre]

Reverts #13201

Fails with

failed: Network is unreachable.
Connecting to launchpad.net (launchpad.net)|2620:2d:4000:1009::f3|:443... failed: Network is unreachable.
 

[oech3]

wget *.deb && dpkg -i *.deb || true

[codspeed-hq]

Merging this PR will degrade performance by 3.24%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

❌ 1 regressed benchmark
✅ 338 untouched benchmarks
⏩ 46 skipped benchmarks¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	uniq_check_chars[(10000, "1")]	14.4 ms	14.9 ms	-3.24%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing revert-13201-fuzz-gnu (ac004c3) with main (10f5eef)}

Footnotes

1. 46 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/misc/tty-eof (passes in this run but fails in the 'main' branch)
Note: The gnu test tests/cp/link-heap is now being skipped but was previously passing.

[sylvestre]

wget *.deb && dpkg -i *.deb || true

i would rather not have a random version of gnu depending on networking

[xtqqczze]

Do GitHub Actions runners have issues with IPv6?

[xtqqczze]

IPv6 works for me locally:

$ curl -s -v -6 -O -L https://launchpad.net/~bamf0/+archive/ubuntu/coreutils-reference/+files/gnu-coreutils_9.11-0ubuntu1~ppa3_amd64.deb
* Host launchpad.net:443 was resolved.
* IPv6: 2620:2d:4000:1009::f3, 2620:2d:4000:1009::3ba
* IPv4: (none)
*   Trying [2620:2d:4000:1009::f3]:443...
* Connected to launchpad.net (2620:2d:4000:1009::f3) port 443

[oech3]

ubuntu-26.04 has coreytils 9.7 which is still newer than 9.5

[xtqqczze]

Can we download and extract GNU coreutils to local directory rather than relying on distribution through the Ubuntu package manager?

[oech3]

It is what the reverted commit does. GNU itself does not distribite binaries.

[oech3]

dpkg is not a problem since it is offline. Different source would cause similar network issue.