chore: pin workflows to specific ubuntu versions

[reubeno]

ubuntu-latest is going to get upgraded to ubuntu-24.04 shortly, but we'd rather intentionally upgrade and work through any issues rather than having them "show up one day".

This PR pins all workflows toubuntu-24.04 with the one notable exception of the native x86_64/Linux build, which we pin to ubuntu-22.04. We do this intentionally because 24.04 brings in a newer version of glibc and decreased compatibility for produced rust binaries.

[github-actions]

Performance Benchmark Report

Benchmark name	Baseline (μs)	Test/PR (μs)	Delta (μs)	Delta %
expand_one_string	3.52 μs	3.52 μs	-0.00 μs	⚪ Unchanged
instantiate_shell	62.31 μs	62.89 μs	0.58 μs	⚪ Unchanged
instantiate_shell_with_init_scripts	28549.33 μs	28844.84 μs	295.51 μs	⚪ Unchanged
parse_bash_completion	2801.31 μs	2775.80 μs	-25.52 μs	🟢 -0.91%
parse_sample_script	4.25 μs	4.30 μs	0.05 μs	⚪ Unchanged
run_echo_builtin_command	91.59 μs	91.86 μs	0.27 μs	⚪ Unchanged
run_one_builtin_command	111.89 μs	110.23 μs	-1.67 μs	⚪ Unchanged
run_one_external_command	1787.77 μs	1802.70 μs	14.93 μs	⚪ Unchanged
run_one_external_command_directly	826.47 μs	824.76 μs	-1.70 μs	⚪ Unchanged

Code Coverage Report: Only Changed Files listed

Package	Base Coverage	New Coverage	Difference
Overall Coverage	🟢 74.67%	🟢 74.67%	⚪ 0%

Minimum allowed coverage is 70%, this run produced 74.67%

[github-actions]

Test Results

    2 files      9 suites   1m 14s ⏱️
  556 tests   556 ✅ 0 💤 0 ❌
1 098 runs  1 098 ✅ 0 💤 0 ❌

Results for commit 6c8939f.

♻️ This comment has been updated with latest results.

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.