test(hardhat): revert to old tests

[Rubilmax]

There are 2 issues to me with the current hardhat tests:

1. they never call the IRM (so gas cost is under-estimated)
2. every signer both supplies and borrows from the market, which is problematic because packed storage slots may be initialized for borrowers whereas they wouldn't in practice (so gas cost is under-estimated)

With the current storage layout, claim 2 is not applicable