number of docs java dcp client can support should be more than Integer.MAX_VALUE

In 7.1, we will support 5TB data per node. It means there will be 5B x 1KB docs per node. In our perf tests, we are using a 4-node cluster, and there are 20B docs. Currently, the number of docs java dcp client can support can't exceed Integer.MAX_VALUE. We need to make java dcp client support more docs.

java.lang.NumberFormatException: For input string: "20000000000"

        at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)

        at java.lang.Integer.parseInt(Integer.java:583)

        at java.lang.Integer.parseInt(Integer.java:615)

        at com.couchbase.client.dcp.perfrunner.PerformanceTestDriver.parseArgs(PerformanceTestDriver.java:105)

        at com.couchbase.client.dcp.perfrunner.PerformanceTestDriver.main(PerformanceTestDriver.java:72)

        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

        at java.lang.reflect.Method.invoke(Method.java:498)

        at org.codehaus.mojo.exec.ExecJavaMojo$1.run(ExecJavaMojo.java:282)

        at java.lang.Thread.run(Thread.java:748)