fix(http_client): fail on VRL compilation errors in query parameters

[thomasqueirozb]

Summary

VRL compilation errors in http_client source query parameters now cause Vector to fail at startup instead of logging a warning and continuing with invalid expressions. This prevents unexpected behavior where malformed VRL expressions would be sent as literal strings in HTTP requests.

Previously, if a VRL expression had a syntax error in a query parameter, Vector would log a warning but continue running, passing the invalid VRL as a literal string. Now, Vector properly fails to start with a clear error message pointing to the compilation issue.

Vector configuration

Invalid configuration (now fails to start):

sources:
  test_http:
    type: http_client
    endpoint: http://httpbin.org/get
    scrape_interval_secs: 60
    query:
      timestamp:
        value: "now("  # Missing closing parenthesis
        type: vrl

sinks:
  console:
    type: console
    inputs:
      - test_http
    encoding:
      codec: json

Valid configuration (works correctly):

sources:
  test_http:
    type: http_client
    endpoint: http://httpbin.org/get
    scrape_interval_secs: 60
    query:
      timestamp:
        value: "now()"
        type: vrl

sinks:
  console:
    type: console
    inputs:
      - test_http
    encoding:
      codec: json

How did you test this PR?

1. Created a test configuration with an invalid VRL expression (now( without closing parenthesis)
2. Ran Vector before the fix - confirmed it logged a warning but continued to start and run
3. Applied the fix to make Query::new(), compile_value(), and compile_param() return Result types
4. Added VrlCompilationError variant to sources::BuildError
5. Rebuilt Vector and ran with the same invalid configuration - confirmed Vector now fails to start with a clear error message
6. Tested with a valid VRL expression (now()) - confirmed Vector starts and runs correctly

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

• Related: chore(internal_logs source): update internal_log_rate_limit tags #24050 (comment)