Revert Longhorn 1.7.2 upgrade
This reverts commit !3039 (merged).
The motivation is the observed increase of failures due to Longhorn in CI pipelines since we have upgraded Longhorn:
(the goal is to have 1.7 in Sylva 1.3, so we should target at solving those issues, but if we keep in main a longhorn version that has issues, it prevents us from doing efficient analysis of CI runs -- need to manually triage failures to tell if they are longhorn failures or not, with the risk of mistakes and missing regressions in the rest of the code)
Edited by Thomas Morin