base: Remove tests making use of Big/LittleEndianOrder Namespace

base: Remove tests making use of Big/LittleEndianOrder Namespace

Unit tests are currently broken.
commit d40f0bc579fb8b10da7181d3a144cd3e9a0a0e59 is removing the
BigEndianOrder and LittleEndianOrder namespace.
Therefore we shouldn't test them and their helpers.

Change-Id: I68a45f264b782334d0a0f725c2c435c27337e757
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/22943
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>