jtools tests fail with missing markerName check

The following tests failed in the JDK18 CI:

   6 sun/tools/jcmd/JcmdOutputEncodingTest.java
   6 sun/tools/jstack/BasicJStackTest.java

There are sightings of this test failure on all platforms in Tier5.

Here's a snippet from one of the log files:

 stderr: []
 exitValue = 0

java.lang.RuntimeException: 'markerName????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????' missing from stdout/stderr

at jdk.test.lib.process.OutputAnalyzer.shouldContain(OutputAnalyzer.java:221)
at BasicJStackTest.testJstackUTF8Encoding(BasicJStackTest.java:67)
at BasicJStackTest.main(BasicJStackTest.java:46)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:127)
at java.base/java.lang.Thread.run(Thread.java:833)

JavaTest Message: Test threw exception: java.lang.RuntimeException: 'markerName????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????' missing from stdout/stderr

JavaTest Message: shutting down test

STATUS:Failed.<EncodeD>60 6d 61 69 6e 27 20 74 68 72 65 77 20 65 78 63 65 70 74 69 6f 6e 3a 20 6a 61 76 61 2e 6c 61 6e 67 2e 52 75 6e 74 69 6d 65 45 78 63 65 70 74 69 6f 6e 3a 20 27 6d 61 72 6b 65 72 4e 61 6d 65 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 e4 bb5 27 20 6d 69 73 73 69 6e 67 20 66 72 6f 6d 20 73 74 64 6f 75 74 2f 73 74 64 65 72 72 </EncodeD>
----------rerun:(40/7002)*----------


The output in question does have a line that contain markerName:

"markerName????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????" #14 prio=5 os_prio=31 cpu=212.90ms elapsed=2.16s tid=0x00007ffc5c00a020 nid=40451 in Object.wait() [0x0000700007e58000]
   java.lang.Thread.State: WAITING (on object monitor)
Thread: 0x00007ffc5c00a020 [0x9e03] State: _at_safepoint _at_poll_safepoint 0
   JavaThread state: _thread_blocked
at java.lang.Object.wait(java.base@18-ea/Native Method)
- waiting on <0x00000007efaae268> (a java.lang.ProcessImpl)
at java.lang.Object.wait(java.base@18-ea/Object.java:338)
at java.lang.ProcessImpl.waitFor(java.base@18-ea/ProcessImpl.java:434)
- locked <0x00000007efaae268> (a java.lang.ProcessImpl)
at jdk.test.lib.process.ProcessTools.executeProcess(ProcessTools.java:445)
at BasicJStackTest.jstack(BasicJStackTest.java:86)
at BasicJStackTest.testJstackUTF8Encoding(BasicJStackTest.java:65)
at BasicJStackTest.main(BasicJStackTest.java:46)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(java.base@18-ea/Native Method)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(java.base@18-ea/NativeMethodAccessorImpl.java:77)
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(java.base@18-ea/DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(java.base@18-ea/Method.java:568)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:127)
at java.lang.Thread.run(java.base@18-ea/Thread.java:833)