refactor: Replace HexStr(o.begin(), o.end()) with HexStr(o)

HexStr can be called with anything that bas `begin()` and `end()` functions,
so clean up the redundant calls.

src/rpc/mining.cpp

@@ -873,7 +873,7 @@ static UniValue getblocktemplate(const JSONRPCRequest& request)
     result.pushKV("height", (int64_t)(pindexPrev->nHeight+1));
 
     if (!pblocktemplate->vchCoinbaseCommitment.empty()) {
-        result.pushKV("default_witness_commitment", HexStr(pblocktemplate->vchCoinbaseCommitment.begin(), pblocktemplate->vchCoinbaseCommitment.end()));
+        result.pushKV("default_witness_commitment", HexStr(pblocktemplate->vchCoinbaseCommitment));
     }
 
     return result;