Docs: Add missing descriptions for `WP_Customize_Header_Image_Control… #29065

Job	Run time
Determine Matrix	5s
Single Site Default / Test current	12m 49s
Single Site Memcached / Test 6.7.0	12m 24s
Multisite Memcached / Test current	13m 27s
Multisite Default / Test current	13m 52s
Multisite Default / Test 6.7.0	13m 3s
Multisite Memcached / Test 6.7.0	12m 21s
Single Site Memcached / Test current	12m 57s
Single Site Default / Test 6.7.0	12m 53s
Slack Notifications / Prepare notifications	5s
Compare / Single Site Default (Publishes)	20s
Compare / Single Site Memcached	48s
Compare / Multisite Memcached	19s
Compare / Multisite Default	47s
Slack Notifications / Success notifications	5s
Slack Notifications / Cancelled notifications	-335s
Slack Notifications / Fixed notifications	-368s
Slack Notifications / Failure notifications	-419s
Failed workflow tasks	-475s
	1h 19m 38s

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