chore: rename Docker test mode environment variable

[AaronFeickert]

Description

It's possible to run Mosaic in an unsafe test mode, which uses lower cut-and-choose parameters to speed up testing. However, this mode is EXTREMELY UNSAFE to use in production. Recent work in #170 controls which mode is built and run in Docker via an environment variable MOSAIC_REDUCED_CIRCUITS.

This PR renames the compiled binary and environment variable to sound scary and help mitigate unintentional production misuse.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature/Enhancement (non-breaking change which adds functionality or enhances an existing one)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactor
• New or updated tests
• Dependency update
• Security fix

Notes to Reviewers

This partially addresses #148, which suggests renaming the feature flag that is used under the hood. That renaming is deferred to later.

Checklist

• I have performed a self-review of my code.
• I have commented my code where necessary.
• I have updated the documentation if needed.
• My changes do not introduce new warnings.
• I have added tests that prove my changes are effective or that my feature works.
• New and existing tests pass with my changes.

Related Issues

Partially addresses #148.

[AaronFeickert]

@Zk2u @sapinb looks like two new vulnerabilities flagged by CI we get to deal with. Both are in rustls-webpki, used by quinn.