fix(bitbucket-server): Record 404 ApiError as halt in webhook

[sentry]

Previously, the Bitbucket Server webhook handler would capture ApiError exceptions with a 404 status code (e.g., when client.get_commits was called with a non-existent commit hash like '0000...0000' during a new branch push) as Sentry errors.

This occurred because ApiError was not explicitly caught before the generic except Exception block, unlike ApiHostError and ApiUnauthorized which correctly record a halt.

This change introduces an except ApiError as e: block. If the ApiError has a 404 status code, lifecycle.record_halt(halt_reason=e) is called, and the processing continues to the next change. This prevents noisy, non-actionable exceptions from being captured in Sentry, treating them as expected conditions.

Legal Boilerplate

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Fixes SENTRY-3ZXM

_{Comment @sentry <feedback> on this PR to have Autofix iterate on the changes.}