Handle proper broadcast becoming avail while there's a manual one

[xmedr]

Overview

This accounts for the edge case where an event with a manually published broadcast link gets access to a proper broadcast link. Previously, the conditionals in the event template would hide the option to unpublish a link if a proper link was available, making it difficult to unpublish that event's manual broadcast if it existed. This allows for that button to be available if both a manual and proper broadcast link exist.

• Connects Make manual broadcast process more robust #1133

Notes

The connected issue describes two improvements, but I'll do this one first because it'll be easier to test now before the second improvement comes in.

Testing Instructions

• Log in to the review app
• Find an event with a proper broadcast and use the manual broadcast url to publish a link for it
  • Can use the event: https://la-metro-cou-patch-manu-sjjazy.herokuapp.com/event/regular-board-meeting-c46ed85d722f/
  • And the publish manual broadcast url: https://la-metro-cou-patch-manu-sjjazy.herokuapp.com/manual_event_link/regular-board-meeting-c46ed85d722f/
• Head back to that event's detail page and attempt to unpublish the link
  • Confirm that the message above the unpublish button appropriately describes the situation
  • Confirm that the link gets unpublished