Recursive Protogalaxy issues

[iakovenkos]

1. Our decider prover and verifier are not flexible enough to handle different fixed proof sizes --> leads to 2-step padding in Protogalaxy Recursive Decider Verifier. After https://github.com/AztecProtocol/aztec-packages/pull/13005 goes in, we have a mechanism to avoid unnecessary padding to CONST_PROOF_SIZE_LOG_N and can delete pad_gate_challenges_for_protogalaxy method.
2. log_circuit_size is a witness --> needs proper handling
3. Analyze whether padding can be done as in ECCVM and Translator, where we can eliminate log_circuit_size thanks to circuit size being a global constant.