Merge branch 'issue/uggrid_parallel' into 'master'

remove specialization for UGGrid since it is fixed in dune-uggrid master

See merge request !218
4 jobs for master in 63 minutes and 31 seconds (queued for 10 minutes and 51 seconds)
Status Job ID Name Coverage
  Test
passed #21943
dune-2.6

00:23:50

passed #21944
dune-2.7

00:31:42

passed #21945
dune-git

00:31:39

passed #21946
dune-git-full

00:39:38