FIX: absolute discount set from client tab (#29352) #4

Job	Run time
gh-travis	0s
phan / Run phan	3m 8s
pre-commit / pre-commit	4m 43s
windows-ci / win-test (windows-latest, 7.4)	7m 42s
phpstan / php-stan (8.2)	16m 4s
	31m 37s

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