twister: Remove unrecognised sections test

The section lists that govern whether the ELF
section is recognised or not are out of date.

A programming bug has rendered the unrecognised
section check unrunnable for years.

Thus, the practically dead code of the
unrecognised section check is removed
in this commit.

Signed-off-by: Lukasz Mrugala <lukaszx.mrugala@intel.com>