[Version-unspecific] Regression test update: lending/refunds.yaml

[Version-unspecific]

This is intended to close #1541 (closed).

When reading through TODOs of the merged !2850 (merged) 'Extend Lending Regression Tests',
I noted that this part

        # 2. Less that this amount results in an over-solvent vault which breaks the
        # invariant.

was I believed already addressed with network version 1.110.0's !2888 (merged)
'Add failed-refund external coins to their pools' BalanceAsset'.

This commit is a proposed update to reflect this; feedback is welcome.