feat(backend)!: update and rename env variables

[golobitch]

Changes proposed in this pull request

• update default values of some env variables
• rename env variable for enabling SPS
• update documentation

Context

fixes #2684

Checklist

• [x] Related issues linked using fixes #number
• [x] Tests added/updated
• [x] Documentation added
• [x] Make sure that all checks pass
• [ ] Bruno collection updated

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