Merge branch 'fix/test-saltwaterintrusion-increase-robustness' into 'master'

Fix/test saltwaterintrusion increase robustness

See merge request !2092 (merged)

(cherry picked from commit 5dbf5596)

326c52a0 [test][1pnc] Cleanup unsused header files 5f769cbc [test][1p2c] Fix dt for saltwaterintrusion for more stable results