refactor: Testnet4 - Replace uint256S("str") -> uint256{"str"}

Ran scripted-diff from 2d9d752.

Follow-up to #29775 which overlapped with work on #30560 (the latter includes the scripted-diff commit).

Author: hodlinator

src/kernel/chainparams.cpp

@@ -320,7 +320,7 @@ class CTestNet4Params : public CChainParams {
         consensus.CSVHeight = 1;
         consensus.SegwitHeight = 1;
         consensus.MinBIP9WarningHeight = 0;
-        consensus.powLimit = uint256S("00000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffff");
+        consensus.powLimit = uint256{"00000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffff"};
         consensus.nPowTargetTimespan = 14 * 24 * 60 * 60; // two weeks
         consensus.nPowTargetSpacing = 10 * 60;
         consensus.fPowAllowMinDifficultyBlocks = true;
@@ -361,8 +361,8 @@ class CTestNet4Params : public CChainParams {
                 1,
                 50 * COIN);
         consensus.hashGenesisBlock = genesis.GetHash();
-        assert(consensus.hashGenesisBlock == uint256S("0x00000000da84f2bafbbc53dee25a72ae507ff4914b867c565be350b0da8bf043"));
-        assert(genesis.hashMerkleRoot == uint256S("0x7aa0a7ae1e223414cb807e40cd57e667b718e42aaf9306db9102fe28912b7b4e"));
+        assert(consensus.hashGenesisBlock == uint256{"00000000da84f2bafbbc53dee25a72ae507ff4914b867c565be350b0da8bf043"});
+        assert(genesis.hashMerkleRoot == uint256{"7aa0a7ae1e223414cb807e40cd57e667b718e42aaf9306db9102fe28912b7b4e"});
 
         vFixedSeeds.clear();
         vSeeds.clear();