Reducing codspeed test flakyness

[ChrisDryden]

Would it be possible to increase the default failure threshold on Codspeed to 3 or 4% instead of 2, I'm finding that a bunch of my PR's are being marked with failed test runs because of it being marked as a regression in performance even though the changes have nothing to do with the benchmarks. For example this change: #9660

[sylvestre]

done, thanks

[xtqqczze]

@sylvestre I've also noticed a lot of PRs failing the CodSpeed check recently, how about increasing the threshold to 5%?

Or even 10%, which is the usual CodSpeed regression threshold.

[xtqqczze]

For example, cp_large_file, dd_copy_partial and sort_key_field are very noisy, see:

• https://github.com/search?q=repo%3Auutils%2Fcoreutils+cp_large_file&type=pullrequests&p=1
• https://github.com/search?q=repo%3Auutils%2Fcoreutils+dd_copy_partial&type=pullrequests&p=1
• https://github.com/search?q=repo%3Auutils%2Fcoreutils+sort_key_field&type=pullrequests&p=1