Breaking: Remove deprecated `--telemetry` flag

[antross]

This was previously removed from the CLI when telemetry was removed in #4734, but resulted in breaks for folks already passing the flag as reported in #4830. These breaks were fixed by still allowing the flag, but ignoring it and marking it as deprecated.

This issue tracks removing the flag entirely which should be considered a breaking change and therefore done as part of the next major release of webhint.