feat: btc-staker improvement(#107) - remove watch staking and post-approval logic

[wnjoon]

This PR includes the removal of the watch-staking endpoint and the post-approval logic as part of issue #107 .

Delete watch-staking endpoint

• Removed related RPC call paths and functions
• Eliminated the watchTxData field and related logic in stakingRequestCmd
• Removed database fields and query/update logic related to watched transactions
• Modified message fields accordingly
• Cleaned up functions that previously had a single execution branch after deleting watched (e.g., buildOwnDelegation)
• Removed test codes related to watch-staking

As a result, calling watch_staking_tx RPC will output the following:

# Run stakerd, babylon, and bitcoind binaries by referring to the contents of README.md. 
# The following shows the log of stakerd.
$ ./stakerd
time="2025-01-31T20:06:59+09:00" level=info msg="Starting App"
time="2025-01-31T20:06:59+09:00" level=info msg="Connecting to node backend: bitcoind"
time="2025-01-31T20:06:59+09:00" level=info msg="Successfully started Prometheus metrics server at 127.0.0.1:2112"
time="2025-01-31T20:06:59+09:00" level=info msg="Successfully connected to node backend: bitcoind"
time="2025-01-31T20:06:59+09:00" level=info msg="Initial btc best block height is: 233384"
time="2025-01-31T20:06:59+09:00" level=info msg="App started"
time="2025-01-31T20:06:59+09:00" level=info msg="Staker Service fully started"
time="2025-01-31T20:06:59+09:00" level=info msg="I[2025-01-31|20:06:59.435] serve                                        msg=\"Starting RPC HTTP server on 127.0.0.1:15812\""

# Call watch_staking_tx RPC
$ curl -X POST -H "Content-Type: application/json" http://127.0.0.1:15812 -d '{"jsonrpc":"2.0","id":1,"method":"watch_staking_tx","params":["","1000","100000000","",[],"","","","","","","","","1000","1"]}'

# Message "Method not found" is returned
{"jsonrpc":"2.0","id":1,"error":{"code":-32601,"message":"Method not found"}}

Remove post-approval flow

• Removed the sendToBabylonFirst option while staking and its related codes
• Removed the delegationActivatedPostApprovalEvent and its related codes and channel
• Removed the handlePostApprovalCmd function and simplifying call hierarchy
• Removed delegationActive field in unbondingTxSignaturesConfirmedOnBabylonEvent
• Removed usePreApprovalFlow field in stakingRequestCmd
• Removed post-approval-related channels and events, and simplified the checkTransactionsStatus function.
• Modified e2e tests that used post-approval logic to use pre-approval logic.

This PR also includes changes to update the tests added to the main branch to use the pre-approval method.

[KonradStaniec]

hey @wnjoon , given this is part of the changes, lets change the base to feature branch and only merge to main after having everything finished.

I have created feature branch for this purpose feat/b-harvest-improve-btc-staker

[wnjoon]

This PR will be merged into the feat/b-harvest-improve-btc-staker branch and then created as a new PR including the removal of local-db state.