improve SSE Apache FPM flush & testing #30547

Job	Run time
Docs	30s
Smoke (latest, Phpunit)	24s
Unit (7.4, Phpunit)	2m 17s
Smoke (latest, CodingStyle)	42s
Behat (8.1, Chrome)	5m 9s
Smoke (latest, StaticAnalysis)	38s
Unit (7.4, Phpunit Lowest)	2m 9s
Behat (8.1, Chrome Lowest)	5m 14s
Unit (8.0, Phpunit)	2m 4s
Behat (8.2, Chrome)	5m 7s
Unit (8.0, Phpunit Lowest)	2m 1s
Unit (8.1, Phpunit)	1m 56s
Behat (8.2, Chrome Lowest)	5m 11s
Unit (8.1, Phpunit Lowest)	2m 3s
Behat (8.3, Chrome)	5m 15s
Unit (8.2, Phpunit)	2m 2s
Behat (8.3, Chrome Lowest)	5m 11s
Unit (8.2, Phpunit Lowest)	2m 5s
Behat (latest, Firefox)	5m 41s
Behat (latest, Chrome Slow)	9m 32s
Unit (8.3, Phpunit)	2m 8s
Behat (latest, Firefox Slow)	8m 0s
Unit (8.3, Phpunit Lowest)	2m 11s
Unit (latest, Phpunit Burn)	5m 19s
	1h 22m 49s

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