[DebugInfo] Remove an outdated test.

64-bit DWARF is supported for most of the sections now, and there are
separate tests for each of them. This test uses a binary input, while
the preferable way is to have a text-based source. Thus, it looks like
this test may be safely removed.

Differential Revision: https://reviews.llvm.org/D80122

Author: igorkudrin