isolateLogEnable can't work in Local Proxy Mode

[francisoliverlee]

i run 2 proxy with broker with the shells, and broker.isolateLogEnable=true

nohup sh bin/mqbroker -c conf/broker1.conf -pc conf/rmq-proxy1.json --enable-proxy > proxy1.out &
nohup sh bin/mqbroker -c conf/broker2.conf -pc conf/rmq-proxy2.json --enable-proxy > proxy2.out &

and find broker log dir is ~/logs/rocketmqlogs/brokerLogDir_IS_UNDEFINED

expected : every broker has its own log dir