[`flake8-bugbear`] Mark the fix for `unreliable-callable-check` as always unsafe (`B004`) (#20318)
## Summary
Resolves #20282
Makes the rule fix always unsafe, because the replacement may not be
semantically equivalent to the original expression, potentially changing
the behavior of the code.
Updated docstring with examples.
## Test Plan
- Added two tests from issue and regenerated the snapshot
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Co-authored-by: Igor Drokin <drokinii1017@gmail.com>
Co-authored-by: Brent Westbrook <36778786+ntBre@users.noreply.github.com>