:fix: set hikari configuration pool to fixed size (more performant) #2595

Job	Run time
Build	5m 32s
test-api-auth	6m 36s
build-javadoc	10m 11s
junit-tests	8m 38s
test-accountAndTranslator	6m 12s
test-brokerAcl	17m 36s
test-broker	26m 54s
test-datastore	15m 24s
test-connection	15m 21s
test-device	5m 2s
test-device-management	12m 23s
test-deviceRegistry	12m 5s
test-endpoint	7m 56s
test-jobEngineRestartOfflineDevice	10m 4s
test-jobEngineRestartOnlineDevice	11m 55s
test-jobEngineRestartOnlineDeviceSecondPart	11m 21s
test-jobEngineServiceStop	13m 2s
test-jobEngineStartOfflineDevice	11m 1s
test-jobEngineStartOnlineDevice	14m 10s
test-jobEngineStepDefinitions	8m 9s
test-jobsAndScheduler	3m 20s
test-jobsIntegration	9m 24s
test-jobsIntegrationBase	9m 42s
test-RoleAndGroup	2m 47s
test-security	5m 32s
test-tag	2m 56s
test-user	3m 47s
test-userIntegration	8m 8s
test-userIntegrationBase	7m 55s
test-api-corsfilter	7m 6s
	4h 50m 9s

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