fix: Added rbac.create flag check for end-user clusterroles in helm chart

[cthtrifork]

Description

I want to install the trivy-operator more than once, as I need them to watch different namespaces with different settings (vex repositories and the like).

However, the operator will try to install non-namespaced items multiple times. This should help fix it, as I will set rbac.create: false on all operators but one and create custom rbac for them.

I believe this is a fix, as rbac.create: false still creates clusterroles today.

Checklist

• I've read the guidelines for contributing to this repository.
• I've added tests that prove my fix is effective or that my feature works.
• I've updated the documentation with the relevant information (if needed).
• I've added usage information (if the PR introduces new options)
• I've included a "before" and "after" example to the description (if the PR is a user interface change).

[CLAassistant]

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