fix(bitbucketserver): replace %w with %v in Logger.Errorf call

[dongjune8931]

Checklist:

• My organization is added to USERS.md.

Logger.Errorf is backed by zap.SugaredLogger, which uses fmt.Sprintfinternally. The %w verb is only meaningful in fmt.Errorf for error wrapping — passing it to Logger.Errorf produces a garbled log line like
%!w(*errors.errorString=&{...}) instead of the actual error message.

Replace %w with %v to produce a human-readable log output, consistent with how other event sources in this codebase handle error logging.

Fixes #3989