Stacktrie getproof

[miha-stopar]

Description

• Fix in the stack trie GetProof method
• Added description for TestTransactions

Issue Link

https://github.com/privacy-scaling-explorations/zkevm-circuits/issues/1752

Type of change

• [x ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update
• [ ] Refactor (no updates to logic)

How Has This Been Tested?

TestTransactions and TestGetProof in zkevm-circuits/geth-utils/gethutil/mpt/witness/gen_witness_transactions_test.go.

[miha-stopar]

Thanks @ChihChengLiang and @adria0 for helping with CI problems!