fix proof-cache regeneration and move to script

[Geometer1729]

Explain your changes:

• Fix a strange issue with nondeterminism in the proof cache regeneration
• Move the script to regenerate it from src/lib/transaction_snark/README.md to scripts/regenerate-proof-cache.sh for ease of use.

Explain how you tested your changes:

• I used this script to regenerate the proof cache for PR Increase app state size #17144

Checklist:

• Dependency versions are unchanged
  • Notify Velocity team if dependencies must change in CI
• Modified the current draft of release notes with details on what is completed or incomplete within this project
• Document code purpose, how to use it
  • Mention expected invariants, implicit constraints
• Tests were added for the new behavior
  • Document test purpose, significance of failures
  • Test names should reflect their purpose
• All tests pass (CI will check this if you didn't)
• Serialized types are in stable-versioned modules
• Does this close issues? List them

[Geometer1729]

!ci-build-me

[Geometer1729]

!ci-bypass-changelog

[Geometer1729]

!ci-build-me

[georgeee]

!ci-bypass-changelog

[Geometer1729]

!ci-bypass-changelog

[Geometer1729]

!ci-build-me

[georgeee]

Left some NITs

[Geometer1729]

!ci-build-me