test: remove autotest grouping

test: remove autotest grouping

Previously, all autotests were grouped into (seemingly arbitrary)
groups. The goal was to run all tests in parallel (so that autotest
finishes faster), but we couldn't just do it willy-nilly because
DPDK couldn't allocate and free hugepages on-demand, so we had to
find autotest groupings that could work memory-wise and still be
fast enough to not hold up shorter tests. The inflexibility of
memory subsystem has now been fixed for 18.05, so grouping
autotests is no longer necessary.

Thus, this commit moves all autotests into two groups -
parallel(izable) autotests, and non-arallel(izable) autotests
(typically performance tests). Note that this particular commit
makes running autotests dog slow because while the tests are now
in a single group, the test function itself hasn't changed much,
so all autotests are now run one-by-one, starting and stopping
the DPDK test application.

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>