Fixed the issue 2481 by not to take PULSAR_MEM from env. (#2484)
Fixed the issue 2481 by not to take PULSAR_MEM from env. (#2484)

### Motivation

Command `./bin/pulsar-admin clusters list` failed with `Error: Could not find or load main class "` in my k8s deployment by using helm charts.

### Modifications

With helm deployment the env var PULSAR_MEM is quoted with `"`, taking it for `pulsar-admin` will make the exec command to be:

```exec /docker-java-home/bin/java -cp '/pulsar/conf:::/pulsar/lib/*:' -Dlog4j.configurationFile=log4j2.yaml -Djava.net.preferIPv4Stack=true '"' -Xms1g -Xmx1g '-XX:MaxDirectMemorySize=1g"' -client -Dio.netty.leakDetectionLevel=disabled ... org.apache.pulsar.admin.cli.PulsarAdminTool /pulsar/conf/client.conf clusters list```

The fix is to take out the use of env var PULSAR_MEM in `conf/pulsar_tools_env.sh`.

### Result

`pulsar-admin` works as expected.

Fixes #2481
merlimat/pulsar,massakam/pulsar,yahoo/pulsar,ArvinDevel/incubator-pulsar,yahoo/pulsar,ArvinDevel/incubator-pulsar,nkurihar/pulsar,nkurihar/pulsar,ArvinDevel/incubator-pulsar,merlimat/pulsar,ArvinDevel/incubator-pulsar,ArvinDevel/incubator-pulsar,merlimat/pulsar,ArvinDevel/incubator-pulsar,jai1/pulsar,ArvinDevel/incubator-pulsar,yahoo/pulsar,massakam/pulsar,merlimat/pulsar,yahoo/pulsar,nkurihar/pulsar,nkurihar/pulsar,jai1/pulsar,yahoo/pulsar,yahoo/pulsar,jai1/pulsar,massakam/pulsar,ArvinDevel/incubator-pulsar,jai1/pulsar,massakam/pulsar,jai1/pulsar,massakam/pulsar,nkurihar/pulsar,nkurihar/pulsar,merlimat/pulsar,nkurihar/pulsar,nkurihar/pulsar,nkurihar/pulsar,massakam/pulsar,jai1/pulsar,jai1/pulsar,jai1/pulsar,merlimat/pulsar,jai1/pulsar