feat(shield): improve regions handling logic to allow override region specific settings without setting region to custom

[maratsal]

What this PR does / why we need it:

improve regions handling logic to allow override region specific settings without setting region to custom. Currently if we want to use alternative collector settings we have to use custom region and specify each of the following values:

sysdig_endpoint:
  region: custom
  api_url: https://www.example.com
  collector:
    host: example.com
    port: 6443

Many customers want to keep using default region settings and update only collector endpoints and use config like below:

sysdig_endpoint:
  region: us2
  collector:
    host: alt-example.com
    port: 443

This PR is addressing that functionality.

Checklist

• Title of the PR starts with type and scope, (e.g. feat(agent,node-analyzer,sysdig-deploy):)
• Chart Version bumped for the respective charts
• Variables are documented in the README.md (or README.tpl in some charts)
• Check GithubAction checks (like lint) to avoid merge-check stoppers
• All test files are added in the tests folder of their respective chart and have a "_test" suffix

[aroberts87]

@maratsal - If I understand the intent of this PR I think what the intent of this change is, is to use sysdig_endpoint.collector.host any time it is specified, correct? If that's true, we could simplify the boolean logic here.

If my understanding is correct, you could apply the simplification to the other areas you've modified as well.

cc @AlbertoBarba

[maratsal]

Maybe, if you can share what you are thinking of - my brain always comes back to couple of checks anyways :D

[aroberts87]

Well, if I'm not mistaken, this change is intended to use sysdig_endpoint.collector.host whether the region field is custom or some valid region, correct? If that's the case, you can simplify the checks here to simply see if sysdig_endpoint.collector.host is non-null.

[maratsal]

updated logic.