API Stop using deprecated LeftAndMain::SCHEMA_HEADER const #543

Job	Run time
CI / Context	1s
CI / Generate matrix	14s
CI / 8.1 prf-low mysql57 phpunit all	2m 43s
CI / Check governance	0s
CI / 8.2 mariadb phpunit all	2m 47s
CI / 8.3 mysql80 phpunit all	2m 32s
CI / 8.3 mysql84 phpunit all	2m 54s
CI / 8.1 mysql57 phplinting	2m 30s
CI / 8.1 mysql57 endtoend root	7m 59s
CI / 8.3 mysql80 endtoend root	8m 8s
CI / 8.1 mysql57 js	4m 23s
CI / Dispatch tag patch release	0s
	34m 11s

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