Function: retireStrat()

This allows the vault to retire the strategy.

Branches and code coverage

Intended branches

• Ensure that no rewards are still left in the Aave Pool.

  Test coverage

• Withdraw everything from the Aave Pool.

  Test coverage

• Transfer all funds to the vault.

  Test coverage

Negative behavior

• Should not be callable by anyone other than the vault.

  Negative test