[Bug]: In `Event.for_site` scope on event model

[ivan-kocienski-gfsc]

Description

This line assumes every partner has an address, and they do not

Found on staging and 78 partners have no address

Acceptance Criteria

• [x] I can view an event that has selected location resolution of event even if some partners in the system do not have addresses

[ivan-kocienski-gfsc]

This line will fix it:

  partner_postcodes: partners.map(&:address).keep_if(&:present?).map { |a| a.postcode.downcase }

[katjam]

Adding to Cycle 30 hotfix milestone as escaped validation

[katjam]

[katjam]

Move to cycle 29 following verification. Made assumption that we'd get a 500 if this was still broken as there are lots of partners on staging without addresses.