[llvm-readobj/elf] - Merge mips-got-overlapped.test to mips-got.test and refine testing.

The `mips-got-overlapped.test` was introduced in D16968 and its intention is
to check that when there is an empty section at the same address as `.got`,
then we are able to locate `.got` and dump it.

The issue is that this test does not test llvm-readelf and uses a precompiled
object. This path starts using YAML instead and merges
mips-got-overlapped.test to mips-got.test.

Differential revision: https://reviews.llvm.org/D86080