Fixes for state storage env vars

[adam-bloom]

What

• The current env var checks for state storage do not properly exclude empty env vars, as is currently implemented for log storage. This means that it is impossible to configure S3 state storage using both kustomize and helm, as those define env vars for the minio state storage (even when they are empty)
• S3 state storage had two different env vars used for region

How

• Borrows the same logic pattern from log storage to apply to state storage
• Consolidate to a single env var for S3 state storage region (these env vars are not currently set by either kustomize or helm)

Recommended reading order

1. x.java
2. y.python

🚨 User Impact 🚨

Are there any breaking changes? What is the end result perceived by the user? If yes, please merge this PR with the 🚨🚨 emoji so changelog authors can further highlight this if needed.

Pre-merge Checklist

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