fix: spend approval txs labels

[blurpesec]

This pull request improves how Ethereum addresses are displayed in transaction approval messages by truncating long addresses for better readability. The changes ensure that both the code and test cases consistently use the shortened address format across transaction categorization and mock data.

Address formatting improvements:

• Introduced a new utility function truncateAddress in utils.ts to shorten Ethereum addresses, displaying the first 7 and last 5 characters with an ellipsis in between.
• Updated the transaction metadata generation in txCategorizeV6.ts to use truncateAddress for the spender field in approval transactions, ensuring all generated approval messages use the truncated address.

Test and mock data updates:

• Modified test cases and mock label data in testCases.mock.ts and txCategorize.test.ts.snap to expect and verify the new truncated address format in approval messages. [1] [2] [3] [4] [5]
• Added comprehensive unit tests for truncateAddress in utils.test.ts to validate its behavior with various address lengths and edge cases.
• Updated existing approval-related tests to expect the truncated address format in their assertions.