Add proper double checked locking for EngineMetrics#getProcessInfo

[devinrsmith]

Follow-up fix for #3591

[devinrsmith]

Observed CI run that produced

java.lang.IllegalStateException: ProcessInfo already created with ID ProcessUniqueId{value=f83c65c4-524a-46b2-83f1-d3a538e88bcb}
        at io.deephaven.process.ProcessInfoConfig.createForCurrentProcess(ProcessInfoConfig.java:71)
        at io.deephaven.engine.table.impl.util.EngineMetrics.getProcessInfo(EngineMetrics.java:36)
        at io.deephaven.engine.tablelogger.impl.memory.UpdatePerformanceLogLoggerMemoryImpl.<init>(UpdatePerformanceLogLoggerMemoryImpl.java:28)
        at io.deephaven.engine.tablelogger.impl.memory.EngineTableLoggersFactoryMemoryImpl.updatePerformanceLogLogger(EngineTableLoggersFactoryMemoryImpl.java:42)
        at io.deephaven.engine.table.impl.perf.UpdatePerformanceTracker.<init>(UpdatePerformanceTracker.java:75)
        at io.deephaven.engine.table.impl.perf.UpdatePerformanceTracker.getInstance(UpdatePerformanceTracker.java:60)
        at io.deephaven.extensions.barrage.table.BarrageTable.<init>(BarrageTable.java:144)
        at io.deephaven.extensions.barrage.table.BarrageRedirectedTable.<init>(BarrageRedirectedTable.java:59)
        at io.deephaven.extensions.barrage.table.BarrageTable.make(BarrageTable.java:397)
        at io.deephaven.extensions.barrage.table.BarrageTable.make(BarrageTable.java:370)
        at io.deephaven.extensions.barrage.util.ArrowToTableConverter.parseSchema(ArrowToTableConverter.java:167)
        at io.deephaven.server.arrow.ArrowFlightUtil$DoPutObserver.onNext(ArrowFlightUtil.java:165)
        at io.deephaven.server.arrow.ArrowFlightUtil$DoPutObserver.onNext(ArrowFlightUtil.java:107)
        at io.grpc.stub.ServerCalls$StreamingServerCallHandler$StreamingServerCallListener.onMessage(ServerCalls.java:262)
        at io.grpc.ForwardingServerCallListener.onMessage(ForwardingServerCallListener.java:33)
        at io.deephaven.server.session.SessionServiceGrpcImpl$SessionServiceCallListener.lambda$onMessage$0(SessionServiceGrpcImpl.java:352)
        at io.deephaven.server.session.SessionServiceGrpcImpl.rpcWrapper(SessionServiceGrpcImpl.java:393)
        at io.deephaven.server.session.SessionServiceGrpcImpl$SessionServiceCallListener.onMessage(SessionServiceGrpcImpl.java:352)