Add tutorials with DuMux as solver into system tests

[Fujikawas]

Checklist:

• I added a summary of any user-facing changes (compared to the last release) in the changelog-entries/<PRnumber>.md.
• I will remember to squash-and-merge, providing a useful summary of the changes of this PR.

[MakisH]

Remember to update.

[MakisH]

To test: trigger the run testsuite manual workflow with:

• use workflow from: dumuxsystemtest (not needed yet, maybe if you change the workflows)
• test suite dumux_test
• no arguments
• branch to take the system tests from: dumuxsystemtest
• logging: DEBUG

[IshaanDesai]

I got further in the debugging and now see the error:

#21 0.167 Cloning into 'dumux-adapter'...
#21 0.678 error: pathspec 'main' did not match any file(s) known to git
#21 ERROR: process "/bin/bash -c git clone --depth 1 https://github.com/precice/dumux-adapter.git &&    cd dumux-adapter &&     if [ -n \"${DUMUX_ADAPTER_PR}\" ]; then git fetch origin pull/${DUMUX_ADAPTER_PR}/head; fi &&     git checkout ${DUMUX_ADAPTER_REF} &&     cd .. &&    dunecontrol --opts=cmake-test.opts --only=dumux-adapter all" did not complete successfully: exit code: 1
------
 > [micro-dumux dumux_adapter 6/6] RUN git clone --depth 1 https://github.com/precice/dumux-adapter.git &&    cd dumux-adapter &&     if [ -n "${DUMUX_ADAPTER_PR}" ]; then git fetch origin pull/${DUMUX_ADAPTER_PR}/head; fi &&     git checkout main &&     cd .. &&    dunecontrol --opts=cmake-test.opts --only=dumux-adapter all:
0.167 Cloning into 'dumux-adapter'...
0.678 error: pathspec 'main' did not match any file(s) known to git
------

It seems like git checkout main for the dumux-adapter did not work, although the main branch does exist.

[MakisH]

You are pulling with --depth 1, asking for the branch main, but the default branch is develop. There is no need for --depth 1 in this case: you want to change to other references, for which you need the full repository.