Tests: Rename some oEmbed test classes as per the naming conventions. #1

Job	Run time
Determine Matrix	0s
${{ ((matrix.multisite && 'Multisite') \|\| 'Single Site') }} ${{ ((matrix.memcached && 'Memcached') \|\| 'Default') }}	0s
matrix.label	0s
Slack Notifications	0s
Failed workflow tasks	0s
	0s

Provide feedback