Remove invalid JFR thread CPU load test case

The following test failed in the JDK14 CI:

jdk/jfr/event/runtime/TestThreadCpuTimeEvent.java

Here's a snippet from the log file:

#section:main
----------messages:(5/295)----------
command: main jdk.jfr.event.runtime.TestThreadCpuTimeEvent
reason: User specified action: run main/othervm jdk.jfr.event.runtime.TestThreadCpuTimeEvent
Mode: othervm [/othervm specified]
Additional options from @modules: --add-modules jdk.jfr,jdk.management
elapsed time (seconds): 10.658
----------configuration:(3/53)----------
Boot Layer
  add modules: jdk.jfr jdk.management

----------System.out:(0/0)----------
----------System.err:(17/1218)----------
java.lang.RuntimeException: assertLessThan: expected that PT0.322S < PT0.28125S
at jdk.test.lib.Asserts.fail(Asserts.java:594)
at jdk.test.lib.Asserts.assertLessThan(Asserts.java:99)
at jdk.test.lib.Asserts.assertLessThan(Asserts.java:82)
at jdk.jfr.event.runtime.TestThreadCpuTimeEvent.testCompareWithMXBean(TestThreadCpuTimeEvent.java:237)
at jdk.jfr.event.runtime.TestThreadCpuTimeEvent.main(TestThreadCpuTimeEvent.java:63)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:127)
at java.base/java.lang.Thread.run(Thread.java:830)

JavaTest Message: Test threw exception: java.lang.RuntimeException: assertLessThan: expected that PT0.322S < PT0.28125S
JavaTest Message: shutting down test

STATUS:Failed.`main' threw exception: java.lang.RuntimeException: assertLessThan: expected that PT0.322S < PT0.28125S
----------rerun:(40/4900)*----------