chainparams: make deployment configuration available on all test networks

This allows unit tests to set `-testactivationheight` and `-vbparams` on
all networks instead of exclusively on regtest. Those are kept
test-network-only when used as startup parameters.

src/init.cpp

@@ -1125,6 +1125,16 @@ bool AppInitParameterInteraction(const ArgsManager& args)
         }
     }
 
+    // Prevent setting deployment parameters on mainnet.
+    if (chainparams.GetChainType() == ChainType::MAIN) {
+        if (args.IsArgSet("-testactivationheight")) {
+            return InitError(_("The -testactivationheight option may not be used on mainnet."));
+        }
+        if (args.IsArgSet("-vbparams")) {
+            return InitError(_("The -vbparams option may not be used on mainnet."));
+        }
+    }
+
     // Also report errors from parsing before daemonization
     {
         kernel::Notifications notifications{};