misc tests fail "assert(existing_f1 == nullptr || existing_f1 == f1) failed: illegal field change"

The following tests failed in the JDK21 CI:

compiler/c2/irTests/blackhole/BlackholeLoadOptoTest.java
serviceability/sa/ClhsdbSymbol.java

Both tests failed the same assertion. For ClhsdbSymbol.java:

# Internal Error (c:\\sb\\prod\\1682440765\\workspace\\open\\src\\hotspot\\share\\oops/cpCache.hpp:149), pid=13168, tid=7996
# assert(existing_f1 == nullptr || existing_f1 == f1) failed: illegal field change
#
# JRE version: Java(TM) SE Runtime Environment (21.0+20) (fastdebug build 21-ea+20-LTS-1644)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 21-ea+20-LTS-1644, mixed mode, tiered, compressed oops, compressed class ptrs, g1 gc, windows-amd64)

For BlackholeLoadOptoTest.java:

# Internal Error (/System/Volumes/Data/mesos/work_dir/slaves/91e16c40-06d4-468a-9fc3-7198a5bb7d5a-S84889/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/fe980f27-86d1-423b-a245-07be8af72791/runs/60211973-4cb2-476e-b5fa-076431105d43/workspace/open/src/hotspot/share/oops/cpCache.hpp:149), pid=41119, tid=24583
# assert(existing_f1 == nullptr || existing_f1 == f1) failed: illegal field change
#
# JRE version: Java(TM) SE Runtime Environment (21.0+20) (fastdebug build 21-ea+20-LTS-1644)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 21-ea+20-LTS-1644, mixed mode, tiered, compressed oops, compressed class ptrs, g1 gc, bsd-amd64)