test: cover liquidator health factor scenarios

[Amlan2006]

Adds liquidation scenario coverage for liquidators with existing unhealthy positions.

• Covers a liquidator receiving collateral shares and improving their health factor
• Covers a competing liquidation where another liquidator liquidates the unhealthy liquidator first

Note: only the targeted scenario suite was run locally.

Testing:

forge test --match-path tests/contracts/spoke/liquidation/Spoke.LiquidationCall.Scenarios.t.sol

[Amlan2006]

@avniculae @Kogaroshi

The failing workflow appears to fail during Foundry setup before running the test suite:

/home/runner/.foundry/bin/foundryup: cannot execute binary file

The targeted suite passes locally:

forge test --match-path tests/contracts/spoke/liquidation/Spoke.LiquidationCall.Scenarios.t.sol