Refactor JVMTI ClassFileLoadHook handling

Make initial load ClassFileLoadHook use the same helper structures as
the retransform path. This makes the system simpler and creates a
single point where changes to the ClassFileLoadHook handling can be
done.

Test: ./test.py --host -j50
Test: ./test.py --redefine-stress --host -j50
Bug: 72064989
Change-Id: I7df9fed267fea497d9efd4f4214506237e63339f