Fix spelling errors in Web3jClient.java

[Dimitrolito]

1. Corrected all instances of web3Serivce to web3Service to ensure consistency with the intended naming convention.
2. Updated:
   • Constructor initialization of web3Service.
   • Usage of web3Service in method calls like rpcRequest, debugTraceBlockByNumber, and getBalanceChangesInBlock.

Motivation

The changes prevent potential confusion and reduce the likelihood of errors related to misspelled variables.

Type of Change

• Bug fix

Checklist:

• Opened an issue or linked to an existing issue (if applicable).
• Performed a self-review of the changes.
• Commented where necessary to clarify the code.