Improve loadinstrumenttest executation time. re #10149

by heavily cut down hrpd instrument used for unit testing
Removed to unit test. re #10149

Removed testExecGEM and testExecHRP. These were added at
early days of loadinstrument adding some of the first instruments
to mantid.

More recently a systemtest has been added that test
that all IDFs loads, hence the tests these performed
are now covered elsewhere
Merge remote-tracking branch 'origin/feature/start_10149'