Simplify finalizer check in `ClassLinker::LoadMethod()`.

Move the special handling for `Object` and `Enum` to the
`ClassLinker::InitWithoutImage()` to simplify the function
used for loading methods for all classes.

Test: test-art-host-gtest
Test: testrunner.py --host --optimizing
Bug: 329196666
Change-Id: I81057802dfa6406045deea53c8029de3622a9ef8