[`pylint`] Make example error out-of-the-box (`PLE1507`) (#19288)
## Summary
Part of #18972
This PR makes [invalid-envvar-value
(PLE1507)](https://docs.astral.sh/ruff/rules/invalid-envvar-value/#invalid-envvar-value-ple1507)'s
example error out-of-the-box.
[Old example](https://play.ruff.rs/a46a9bca-edd5-4474-b20d-e6b6d87291ca)
```py
os.getenv(1)
```
[New example](https://play.ruff.rs/8348d32d-71fa-422c-b228-e2bc343765b1)
```py
import os
os.getenv(1)
```
The "Use instead" section was also updated similarly.
## Test Plan
<!-- How was it tested? -->
N/A, no functionality/tests affected
