Fix system tests

Request the redemption via the `depositorBridgeHandle.requestRedemption`
directly instead of  `requestRedemption` function. After refactoring in
`#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
`#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.

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(