Remove oat_data_begin checks from OatFile.

Make it a CHECK() directly in the ImageSpace instead. This
check was a rather weird way to prevent the use of dlopen()
for boot image on host because it would load the oat file
at the wrong address. This is now done by refusing to use
dlopen() on host when we have a memory `reservation`.

Also clean up affected files for bugprone-argument-comment.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Bug: 77856493
Change-Id: I6f0f9d5a0542574017d98acc2f4f30a585b483f4