Merge bitcoin#22135: CRegTestParams: Use args instead of gArgs.

5f23531 CRegTestParams: Use `args` instead of `gArgs`. (Kiminuo)

Pull request description:

  This PR is a very minor follow-up to bitcoin#13311.

  I believe that `gArgs` was just overlooked at the modified line.

ACKs for top commit:
  MarcoFalke:
    cr ACK 5f23531

Tree-SHA512: f4e4ed6b23fca60e88825b502f20a1341ee2e4429bc8a2a7e419057adb643abda11be2061fe7ee076931657736e629aff88fd2c33737c84c330dc9d64f368c30

src/chainparams.cpp

@@ -423,7 +423,7 @@ class CRegTestParams : public CChainParams {
         pchMessageStart[2] = 0xb5;
         pchMessageStart[3] = 0xda;
         nDefaultPort = 18444;
-        nPruneAfterHeight = gArgs.GetBoolArg("-fastprune", false) ? 100 : 1000;
+        nPruneAfterHeight = args.GetBoolArg("-fastprune", false) ? 100 : 1000;
         m_assumed_blockchain_size = 0;
         m_assumed_chain_state_size = 0;