[GR-54994] Remove duplicate ThreadSleep JFR events and use nanosNow() to timestamp JFR chunks.

[roberttoyonaga]

Related issues: #9201 and #9199

This pull request:

1. Updates JfrTicks to use the new PlatformTimeUtils.nanosNow() method. This ensures that borrowed java-level JDK code that uses JVM.nanosNow() is using the same clock that we timestamp chunk files with. See the comment here. Currently we use System.currentTimeMillis() to timestamp chunks, which is a different clock and only has ms precision. This might cause inconsistencies if JDK code uses JVM.nanosNow() and compares it to times retrieved from System.currentTimeMillis() .
2. Removes the duplicate emission of jdk.ThreadSleep events from SVM code. Previously the events were being emitted from borrowed Java-level JDK code and then again from SubstrateVM code.

Before

After:

[christianhaeubl]

Thanks, this PR will be merged in the next few days.