fix: gardener has exposed kubelet CA to end user

[rakesh-garimella]

Description

Changes proposed in this pull request (what was done and why):

• Gardener has exposed kubelet CA to end user so we can enable TLS verification for kubelet stats receiver
• Also add some comments to explain why insecure_skip_verify is set to false

Changes refer to particular issues, PRs or documents:

• Expose the kubelet CA to end-users gardener/gardener#11362
• kubeletstatsreceiver should verify the server side cert #1792

Traceability

• The PR is linked to a GitHub issue.
• The follow-up issues (if any) are linked in the Related Issues section.
• If the change is user-facing, the documentation has been adjusted.
• If a CRD is changed, the corresponding Busola ConfigMap has been adjusted.
• The feature is unit-tested.
• The feature is e2e-tested.

[a-thaler]

That will not work without additional config. You need to tell the receiver from where to get the kublet CS as it is located in a gardener specific configmap.