feat(helm): pass arbitrary env vars to trivy

[jouve]

Description

fix #3206

with the following values.yaml

trivy:
  extraEnvVars:
    FOO: bar
    TOTO: |
      titi
      multi
      line

the chart has the following diff in the configmap:

@@ -47,6 +47,11 @@
   TRIVY_DEBUG: "false"
   TRIVY_SKIP_UPDATE: "false"
   TRIVY_DB_REPOSITORY: "ghcr.io/aquasecurity/trivy-db"
+  FOO: bar
+  TOTO: |
+    titi
+    multi
+    line

Checklist

• I've read the guidelines for contributing to this repository.
• I've followed the conventions in the PR title.
• 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).
• [x ] 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]

All committers have signed the CLA.

[knqyf263]

@chen-keinan Could you take a look?

[chen-keinan]

@jouve lgtm 🚀