test(connector-besu): jest migrate v21-sign-transaction-endpoint.test.ts

[suumona]

Migrate all existing test cases for the v21-sign-transaction logs endpoint to Jest.

./packages/cactus-test-plugin-ledger-connector-besu/src/test/typescript/integration/plugin-validator-besu/v21-sign-transaction-endpoint.test.ts

[petermetz]

@suumona Are you planning on working on this by any chance? If yes then I can assign it to you.

[suumona]

Hi @petermetz,
Yes, please assign this issue to me.

[petermetz]

@suumona Done, thank you in advance for the contributions! :-)