Merge branch 'issue/config_h' into 'master'

unify config.h includes

See merge request !208
4 jobs for master in 47 minutes and 9 seconds (queued for 28 minutes and 45 seconds)
Status Job ID Name Coverage
  Test
passed #21194
dune-2.6

00:23:46

passed #21195
dune-2.7

00:31:18

passed #21196
dune-git

00:31:08

passed #21197
dune-git-full

00:42:49