Investigate suspected self-comparison bug in ForceMethodParametersInvocationsDiagnosticsAnalyzer

[credfeto]

Spotted while surveying the analyzer package for #455 (performance pass). Not a perf item — a suspected correctness bug.

ForceMethodParametersInvocationsDiagnosticsAnalyzer.cs:194 appears to compare a value to itself (self-comparison), which would make the comparison always true/false regardless of input, short-circuiting whatever check it was meant to perform.

• Confirm whether this is a real bug (vs. an intentional/harmless tautology) by reading the surrounding logic
• If real, add a regression test that reproduces the incorrect behavior before fixing
• Fix in its own PR, separate from the performance-pass PRs, since it's a behavior change rather than perf-only

This should land independently of the #455 phases so it doesn't get bundled with perf-only changes.