Fix system tests

Request the redemption via the `depositorBridgeHandle.requestRedemption`
directly instead of  `requestRedemption` function. After refactoring in
`keep-network#632`, the `requestRedemption` requests redemption via tBTC token
contract. In the current deposit scenario, we do not pass the vault
address so the `depositor` does not actually have any tBTC tokens so we
can't request redemption via `requestRedemption` fn with changes from
`keep-network#632`. We are going to add a new scenario where we pass the TBTC vault
address to the `revealDeposit` function to test the new mechanism of
requesting the redemption via tBTC token contract in follow-up work.

Author: r-czajkowski

system-tests/test/deposit-redemption.test.ts

@@ -262,12 +262,11 @@ describe("System Test - Deposit and redemption", () => {
             systemTestsContext.depositorBitcoinKeyPair.publicKey.compressed
           )}`
 
-          await TBTC.requestRedemption(
+          await depositorBridgeHandle.requestRedemption(
             systemTestsContext.walletBitcoinKeyPair.publicKey.compressed,
             sweepUtxo,
             redeemerOutputScript,
             requestedAmount,
-            depositorBridgeHandle
           )
 
           console.log(