fix(datastore): improve performances on messages store #1777

Job	Run time
Build	7m 6s
test-tag	2m 11s
test-broker	26m 53s
test-brokerAcl	17m 32s
test-datastore	15m 38s
test-connection	14m 37s
test-device	5m 11s
test-device-management	13m 37s
test-jobsIntegrationBase	10m 7s
test-security	5m 24s
test-user	3m 47s
test-userIntegration	8m 36s
test-userIntegrationBase	8m 18s
junit-tests	8m 13s
test-accountAndTranslator	6m 22s
test-deviceRegistry	9m 20s
test-endpoint	8m 12s
test-jobEngineRestartOfflineDevice	10m 47s
test-jobEngineRestartOnlineDevice	12m 16s
test-jobEngineRestartOnlineDeviceSecondPart	10m 20s
test-jobEngineServiceStop	13m 27s
test-jobEngineStartOfflineDevice	11m 47s
test-jobEngineStartOnlineDevice	13m 45s
test-jobsAndScheduler	2m 37s
test-jobEngineStepDefinitions	8m 48s
test-jobsIntegration	9m 54s
test-RoleAndGroup	2m 33s
build-javadoc	10m 29s
	4h 37m 47s

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