Removed unnecessary test due to introduction of ST_FromGDALRaster()

git-svn-id: http://svn.osgeo.org/postgis/trunk@11495 b70326c6-7e19-0410-871a-916f4a2858ee
Refactored use of out-db rasters for regression tests

git-svn-id: http://svn.osgeo.org/postgis/trunk@11496 b70326c6-7e19-0410-871a-916f4a2858ee