test that sudo respects /etc/security/limits

[japaric]

cc #629

this tests sudo, rather than su but likely we want both to behave the same. su tests will be added in a follow up PR that depends on #640

[github-actions[bot]]

Number of dependencies and binary size impact report

Metric	main	PR #645	Delta
Direct dependencies	5	5	-
Total dependencies	10	10	-
Binary size	1.1 MiB	1.1 MiB	-
Text size	652.3 KiB	652.3 KiB	-

Dependencies diff

```diff └─ sudo-rs [v0.2.0-dev.20230703] ├─ glob [v0.3.1] ├─ libc [v0.2.147] ├─ log [v0.4.19] ├─ signal-hook [v0.3.15] | ├─ libc [v0.2.147] | ├─ signal-hook-registry [v1.4.1] | | └─ libc [v0.2.147] | └─ cc [v1.0.79] └─ signal-hook-registry [v1.4.1] ```

[codecov[bot]]

Codecov Report

Patch coverage has no change and project coverage change: +0.11 :tada:

Comparison is base (d9b6616) 86.49% compared to head (9ee393d) 86.61%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #645 +/- ## ========================================== + Coverage 86.49% 86.61% +0.11% ========================================== Files 61 61 Lines 8644 8644 ========================================== + Hits 7477 7487 +10 + Misses 1167 1157 -10 ``` [see 4 files with indirect coverage changes](https://app.codecov.io/gh/memorysafety/sudo-rs/pull/645/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=memorysafety)

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