Wrong JSON path is used to check DB lock status while switching DR clusters

[leonliao]

According to release notes of 6.3.9, the status json output for database lock status has been updated.

Replaced cluster.database_locked status field with cluster.database_lock_state, which contains two subfields: locked (boolean) and lock_uid (which contains the database lock uid if the database is locked). (PR #2058)

But the code to check DB lock status is still using old JSON path.

bool getLockedStatus(StatusObjectReader statusObj) {
	try {
		StatusObjectReader statusObjCluster = statusObj["cluster"].get_obj();
		return statusObjCluster["database_locked"].get_bool();
	} catch (std::runtime_error& e) {
		TraceEvent(SevWarn, "DBA_GetLockedStatusFail").detail("Error", e.what());
		throw backup_error();
	}
}

This is causing errors while switching over.

<Event Severity="20" Time="1641869341.175349" DateTime="2022-01-11T02:49:01Z" Type="DBA_GetLockedStatusFail" ID="0000000000000000" Error="JSON path doesn't exist" ThreadID="886029773038070683" Machine="127.0.0.1:8661" LogGroup="default" />

Will submit a PR to solve it.