feat(unit tests): respect color flag for tests

[VanjaRo]

Summary

• vector test now disables ANSI color when non-interactive (e.g., CI), preventing escape codes in logs.
• All VRL diagnostics (compile errors/warnings, runtime errors) respect the global color setting.
• Minor: fix a logging field typo in runtime init debug message.

Vector configuration

# Default (auto): color enabled only when stdout is a TTY
vector test

# Force enable color
vector --color always test

# Force disable color
vector --color never test

# Using environment variable
VECTOR_COLOR=always vector test
VECTOR_COLOR=never vector test

# Non-interactive scenario (auto → no color)
vector test | tee out.txt

How did you test this PR?

• Verified TTY detection: --color auto shows ANSI when run in an interactive terminal, and no ANSI when piped/redirected.
• Forced behaviors validated with --color always|never and VECTOR_COLOR=always|never.
• Confirmed VRL diagnostics across validate, conditions (src/conditions/vrl.rs), remap transform, HTTP server auth, and HTTP client query parameters show colored output only when enabled.
• Ensured init_logging and downstream modules receive the same global color preference via set_global_color(...).
• Spot-checked that CI-like environments (piped output) produce log lines without ANSI sequences.

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the no-changelog label to this PR.

References

• Closes: vector test should not colorize unless it is running interactively #23717

[pront]

Thanks @VanjaRo

[VanjaRo]

Sry, I accidentally pushed the wrong class name for multiple Diagnostics. Fixed.

[pront]

Sry, I accidentally pushed the wrong class name for multiple Diagnostics. Fixed.

Did you have a chance to repeat the tests with the latest version?

[VanjaRo]

Sry, I accidentally pushed the wrong class name for multiple Diagnostics. Fixed.

Did you have a chance to repeat the tests with the latest version?

Yep, tests and check –– same output as master.