Change "room has loaded all history" to qCDebug #1443

Job	Run time
CI (ubuntu-22.04, 6.4, e2ee)	55s
CI (ubuntu-22.04, 6.4)	1m 6s
CI (ubuntu-22.04, 6.4, GCC, e2ee)	1m 4s
CI (ubuntu-22.04, 6.4, GCC)	1m 20s
CI (ubuntu-22.04, 5.15, e2ee)	1m 18s
CI (macos-11, 6.4, e2ee)	10m 15s
CI (macos-11, 6.4)	5m 50s
CI (macos-11, 5.15, e2ee)	8m 6s
CI (windows-2019, 6.4, e2ee)	1m 50s
CI (windows-2019, 6.4)	2m 13s
CI (windows-2019, 5.15, e2ee)	2m 14s
CI (ubuntu-22.04, 5.15, e2ee, update-api, codeql)	1m 23s
CI (ubuntu-22.04, 5.15, GCC, update-api)	1m 2s
	38m 36s

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