[test][2p] remove old adaptive tests and cornerpoint test

test/porousmediumflow/2p/implicit/CMakeLists.txt

test/porousmediumflow/2p/implicit/cc2pcornerpointproblem.hh

...ousmediumflow/2p/implicit/cc2pcornerpointspatialparams.hh

test/porousmediumflow/2p/implicit/grids/hardsmall.grdecl

test/porousmediumflow/2p/implicit/grids/rectangle-domain.geo

test/porousmediumflow/2p/implicit/grids/rectangle-domain.msh

test/porousmediumflow/2p/implicit/test_boxadaptive2p.cc

test/porousmediumflow/2p/implicit/test_boxadaptive2p.input

test/porousmediumflow/2p/implicit/test_cc2pcornerpoint.cc

test/porousmediumflow/2p/implicit/test_cc2pcornerpoint.input

test/porousmediumflow/2p/implicit/test_ccadaptive2p.cc

test/porousmediumflow/2p/implicit/test_ccadaptive2p.input