Disable RmiTest for ServerLegacy_stub

[bantonsson]

Fails sometimes with NegativeArraySizeException in TimelinePrinter

https://output.circle-artifacts.com/output/job/4aa15e53-496f-4038-9073-00e84c258bc5/artifacts/0/reports/dd-java-agent/instrumentation/rmi/tests/test/classes/RmiTest.html#Client%20call%20using%20ServerLegacy_stub%20creates%20spans

java.lang.NegativeArraySizeException: -7
	at java.lang.AbstractStringBuilder.<init>(AbstractStringBuilder.java:86)
	at java.lang.StringBuilder.<init>(StringBuilder.java:116)
	at datadog.trace.agent.test.checkpoints.TimelinePrinter.repeat(TimelinePrinter.groovy:78)
	at datadog.trace.agent.test.checkpoints.TimelinePrinter.print(TimelinePrinter.groovy:42)
	at datadog.trace.agent.test.checkpoints.TimelineTracingContextTracker.print(TimelineTracingContextTracker.groovy:147)
	at org.spockframework.mock.runtime.ByteBuddyMethodInvoker.respond(ByteBuddyMethodInvoker.java:20)
	at org.spockframework.mock.runtime.MockInvocation.callRealMethod(MockInvocation.java:59)
	at org.spockframework.mock.CallRealMethodResponse.respond(CallRealMethodResponse.java:30)
	at org.spockframework.mock.runtime.MockController.handle(MockController.java:50)
	at org.spockframework.mock.runtime.JavaMockInterceptor.intercept(JavaMockInterceptor.java:72)
	at org.spockframework.mock.runtime.ByteBuddyInterceptorAdapter.interceptNonAbstract(ByteBuddyInterceptorAdapter.java:35)
	at datadog.trace.agent.test.AgentTestRunner.cleanup(AgentTestRunner.groovy:297)