Editor: Fix complex variation selectors when using selectors API. #21198

Job	Run time
Determine Matrix	3s
Single Site Default / Test 6.7.0	13m 20s
Single Site Default / Test current	13m 25s
Multisite Default / Test 6.7.0	13m 36s
Multisite Default / Test current	14m 43s
Single Site Memcached / Test 6.7.0	13m 14s
Single Site Memcached / Test current	13m 10s
Multisite Memcached / Test current	12m 39s
Multisite Memcached / Test 6.7.0	13m 18s
Slack Notifications / Prepare notifications	5s
Compare / Single Site Default (Publishes)	17s
Compare / Multisite Default	9s
Compare / Single Site Memcached	18s
Compare / Multisite Memcached	9s
Slack Notifications / Success notifications	3s
Slack Notifications / Failure notifications	0s
Slack Notifications / Cancelled notifications	0s
Slack Notifications / Fixed notifications	0s
Failed workflow tasks	0s
	1h 48m 29s

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