Add support for `IMG` tags with `fetchpriority=low` or `fetchpriority=auto` #33201

Job	Run time
Determine Matrix	3s
Multisite Default / Test before	6m 40s
Single Site Default / Test current	6m 40s
Multisite Memcached / Test before	6m 40s
Single Site Default / Test before	6m 40s
Single Site Memcached / Test current	6m 41s
Single Site Memcached / Test before	6m 40s
Multisite Memcached / Test current	6m 40s
Multisite Default / Test current	6m 40s
Slack Notifications	0s
Failed workflow tasks	1s
matrix.label	0s
	53m 25s

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