Update congregate.conf.template

Overview

• Removes comment from template file when using congregate stage-wave command linked here - https://gitlab.com/gitlab-org/professional-services-automation/tools/migration/congregate/-/blob/master/docs/using-congregate.md?ref_type=heads#stage-wave
• During a customer engagement the command congregate stage-wave wave_name was failing with error thrown from line 81 here - https://gitlab.com/gitlab-org/professional-services-automation/tools/migration/congregate/-/blob/master/congregate/cli/stage_wave.py#L81
• Removal of the comment after the line 37 which starts with wave_spreadsheet_path removed the error and the CSV file was found
• Slack discussion and resolution - https://gitlab.slack.com/archives/CRYB20ZA5/p1712691218059579

Tasks

• Update docs if needed (workflow, runbooks, README, migration metrics, etc.)

Acceptance Criteria

• Existing UTs pass locally