cli: "result show": Don't simplify resultclass name

Previously, if the resultclass name started with the same "words" that
the benchmark name ended with, we would remove them from the resultclass
name. The intent was to reduce the required column width for the table
when the information was repeated.

But this gets confusing when we want to grab the resultclass name for
use with bisection. So let's revert the behavior and accept it might
cost a bit more screen real estate in some cases.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>