[LLDB] Switch from using member_clang_type.GetByteSize() to...

[LLDB] Switch from using member_clang_type.GetByteSize() to member_type->GetByteSize() in ParseSingleMember

We have a bug in which using member_clang_type.GetByteSize() triggers record
layout and during this process since the record was not yet complete we ended
up reaching a record that had not been layed out yet.
Using member_type->GetByteSize() avoids this situation since it relies on size
from DWARF and will not trigger record layout.

For reference: rdar://77293040

Differential Revision: https://reviews.llvm.org/D102445