Update init checks to be less restrictive

[duhow]

As of #283 restrictive check, Docker images after 22.6.0 are not working properly for us.

We are running LibreNMS in Kubernetes, where we have the config.php mounted as ConfigMap (read-only for the file system), and also Redis has disabled FLUSHDB as a safety measure.

Changes applied in here:

• Ignore errors if cannot clean config.d folder initially.
• Create new config.d files only if folder is writable.
• Update chown folders only if are writtable.
• Ignore if cache:clear fails. (Redis)

[murrant]

Question, how do you clear possibly incompatible cached data from redis?

[duhow]

I haven't had the "need", but from the current test 22.6 to 23.4 I didn't find any "incompatible issues".
@murrant Would it help to show a warning message but continue running the software?

[crazy-max]

This should be an opt-in opt

[duhow]

@crazy-max can you review changes again and validate?

[LoveSkylark]

I struggled with this Kubernetes + config.php and ultimately I solved this using lnms instead:
https://github.com/LoveSkylark/LibreNMS-Helm/blob/main/templates/jobs-install.yaml