Merge bitcoin/bitcoin#30721: refactor: Testnet4 - Replace uint256S("str") -> uint256{"str"}

49f9b64 refactor: Testnet4 - Replace uint256S("str") -> uint256{"str"} (Hodlinator)

Pull request description:

  Ran scripted-diff from 2d9d752:
  ```
  sed -i --regexp-extended -e 's/\buint256S\("(0x)?([^"]{64})"\)/uint256{"\2"}/g' $(git grep -l uint256S)
  ```

  Follow-up to Testnet4 introduction #29775 which overlapped with work on `uint256` `consteval` ctor #30560 (the latter includes the scripted-diff commit).

  Going forward `uint256{}` should be used for constants instead of `uint256S()`.

ACKs for top commit:
  maflcko:
    review-ACK 49f9b64 🐮
  fjahr:
    ACK 49f9b64

Tree-SHA512: 94fe5d9f1fb85e9ce5c3c4c5e4c31667e8cbb55ee691a4b5b3ae4172ccac38230281071023663965917f188b4c19bdf67afd4e3cdf69d89e97c65faea88af833

Author: fanquake

src/kernel/chainparams.cpp

@@ -319,7 +319,7 @@ 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;
@@ -360,8 +360,8 @@ 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();