fuzz: addrman, avoid `ConsumeDeserializable` when possible #27918

Using specific functions like ConsumeService, ConsumeAddress and ConsumeNetAddr may be more effective than using ConsumeDeserializable. They always return some value while ConsumeDeserializable may return std::nullopt.

E.g.: In this part of the code, if op_net_addr is std::nullopt, we basically generated the addresses (if so) unnecessarily, because we won't be able to use them:

std::vector<CAddress> addresses;
LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), 10000) {
    const std::optional<CAddress> opt_address = ConsumeDeserializable<CAddress>(fuzzed_data_provider);
    if (!opt_address) {
        break;
    }
    addresses.push_back(*opt_address);
}
const std::optional<CNetAddr> opt_net_addr = ConsumeDeserializable<CNetAddr>(fuzzed_data_provider);
if (opt_net_addr) {
    addr_man.Add(addresses, *opt_net_addr, std::chrono::seconds{ConsumeTime(fuzzed_data_provider, 0, 100000000)});
}

Also, if we are not calling Add effectively, it would also be affect other functions that may "depend" on it.

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Conflicts

Reviewers, this pull request conflicts with the following ones:

• #25284 (net: Use serialization parameters for CAddress serialization by MarcoFalke)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

lgtm

In theory one could use the nullopt state to break a loop or exit early (for example with a different exit code, c.f. #27552), but given that this fuzz target checks ConsumeBool (which returns false on empty input) on each iteration before continuing, this seems fine for this fuzz target.

Code review ACK 025fda0a76893d09d19ec9a6c0ba86ad11c466f7