twister: improve handling of ELF file parsing

We have been dealing with missing and multiple binaries the same way and
both would result in a build error, which is not accurate. multiple
binaries in the build directory are fine, we just need to pick the right
one for parsing.

If we get no binaries, raise an exception and report failure, however,
if we have multiple binaries, filter intermediate artifacts out and
parse what remains.

qemu binaries generated after a run are also being filtered here. Those
are not build artificats and appear only after running in qemu. However
they have been causing issues on retries.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>