test: add shell-completion case for hidden BoolWithInverseFlag #2405

Follow-up from review of #2388.

Summary

PR #2388 changed printFlagSuggestions in help.go to skip flags via the VisibleFlag/IsVisible() interface instead of the previous flag.(*BoolFlag) assertion. The previous check only skipped hidden bool flags, and because the *BoolFlag assertion does not match the *BoolWithInverseFlag concrete type, hidden BoolWithInverseFlags were also leaked into shell completion suggestions.

That leak is now fixed by the interface-based check, but the regression test table in TestDefaultCompleteWithFlags only covers the BoolFlag (hidden-bool) and StringFlag (new in #2388) cases.

Proposed change

Add a BoolWithInverseFlag case to the TestDefaultCompleteWithFlags table (e.g. a hidden --excellent BoolWithInverseFlag) to lock in the fix for this type too.

Impact

• Low risk; test-only change.