cleaned up assembling and dirichlet BC

4 jobs for feature/operators_in_dofmatrix in 21 minutes and 10 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Test
passed #6694
debian:10 clang-6-libcpp-17

00:21:09

passed #6693
debian:10 gcc-8-17

00:13:10

passed #6695
debian:9 gcc-6-14

00:12:34

passed #6696
ubuntu:18.04 clang-6-17

00:20:06