Ensure empty plugin settings are saved correctly #7314

Job	Run time
Javascript	3m 49s
Client	1m 14s
UI (0)	34m 18s
PHP (UnitTests, 7.2, Mysql, PDO_MYSQL)	3m 2s
PHP (UnitTests, 8.2, Mariadb, PDO_MYSQL)	3m 11s
UI (1)	17m 56s
PHP (UnitTests, 8.4, Mysql, MYSQLI)	1m 13s
UI (2)	18m 32s
PHP (SystemTestsPlugins, 7.2, Mysql, PDO_MYSQL)	13m 20s
UI (3)	14m 46s
PHP (SystemTestsPlugins, 8.2, Mariadb, PDO_MYSQL)	11m 51s
PHP (SystemTestsPlugins, 8.4, Mysql, MYSQLI)	16m 1s
PHP (SystemTestsCore, 7.2, Mysql, PDO_MYSQL)	9m 43s
PHP (SystemTestsCore, 8.2, Mariadb, PDO_MYSQL)	9m 22s
PHP (SystemTestsCore, 8.4, Mysql, MYSQLI)	10m 36s
PHP (IntegrationTestsCore, 7.2, Mysql, PDO_MYSQL)	12m 58s
PHP (IntegrationTestsCore, 8.2, Mariadb, PDO_MYSQL)	11m 32s
PHP (IntegrationTestsCore, 8.4, Mysql, MYSQLI)	15m 18s
PHP (IntegrationTestsPlugins, 7.2, Mysql, PDO_MYSQL)	32m 56s
PHP (IntegrationTestsPlugins, 8.2, Mariadb, PDO_MYSQL)	32m 33s
PHP (IntegrationTestsPlugins, 8.4, Mysql, MYSQLI)	40m 5s
	5h 14m 16s

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