[llvm-readobj/elf] - Refine the malformed-pt-dynamic.test.

This is splitted out from D85519, but significantly reworked.

Changes:
1) This test was changed to stop using python.
2) Use NoHeaders: true instead of `llvm-objcopy --strip-sections`.
3) Test llvm-readelf too (not just llvm-readobj).
4) Simplify the YAML used a bit (e.g. remove PT_LOAD).
5) Test 2 different cases: objects with section header table and without.

Differential revision: https://reviews.llvm.org/D86073