2p2c water-air and fuelcell/remediation tests fail due to !1615

The following tests fail on buildbot due to the changes in the viscosity calculation from !1615 (merged)

dumux (some have a singular matrix and do not converge at all)

119 - test_2p2cni_waterair_box (Failed)
120 - test_2p2cni_waterair_buoyancy_box (Failed)
121 - test_2p2cni_waterair_tpfa (Failed)

dumux-lecture (here only the reference solution does not match anymore)

11 - fuelcell (Failed)
22 - remediationscenariosexercise (Failed)