Remove substransaction from wiki event creation

Removes a use of `safe_find_or_create_by!` when
adding a wiki-related Event.

Changelog: fixed

app/services/wiki_pages/event_create_service.rb

@@ -10,11 +10,9 @@ module WikiPages
     end
 
     def execute(slug, page, action, event_fingerprint)
-      event = Event.transaction do
       wiki_page_meta = WikiPage::Meta.find_or_create(slug, page)
 
-        ::EventCreateService.new.wiki_event(wiki_page_meta, author, action, event_fingerprint)
-      end
+      event = ::EventCreateService.new.wiki_event(wiki_page_meta, author, action, event_fingerprint)
 
       ServiceResponse.success(payload: { event: event })
     rescue ::EventCreateService::IllegalActionError, ::ActiveRecord::ActiveRecordError => e

spec/services/wiki_pages/event_create_service_spec.rb

@@ -34,10 +34,6 @@ RSpec.describe WikiPages::EventCreateService do
       it 'does not create an event' do
         expect { response }.not_to change(Event, :count)
       end
-
-      it 'does not create a metadata record' do
-        expect { response }.not_to change(WikiPage::Meta, :count)
-      end
     end
 
     it 'returns a successful response' do