fix(psa-checker): only fail if PSS violations are found

[amitchell-moz]

Description

Modify psa-checker to only fail if PSS violations are found.

Currently it will fail if a chart doesn't render, which tends to confuse users; this PR makes it so that will print a warning & pass the job, which is how the validate & helmdiff jobs behave.

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Old behavior:

• Fail when one chart passes and one fails to render: https://github.com/mozilla/webservices-infra/actions/runs/19875028211/job/56960262267?pr=8635
• Fail in platform-shared: https://github.com/mozilla/global-platform-admin/actions/runs/20036540116/job/57459570627

New behavior:

• Pass when one chart validates and one chart didn't render: https://github.com/mozilla/webservices-infra/actions/runs/20045553210/job/57490211960
• Pass when platform-shared fails to render (like it always does): https://github.com/mozilla/global-platform-admin/actions/runs/20045710877/job/57490735774?pr=4926

Also validated that it still properly fails when PSS violations are found: https://github.com/mozilla/webservices-infra/actions/runs/20045602041/job/57490375853?pr=8726

Related Tickets & Documents

• MZCLD-1376
• SREIN-766