refactor: move superblock sync check inside !IsTestChain() guard

Move the superblock sync check in getblocktemplate inside the existing
!IsTestChain() block, matching the pattern used by the IBD check.
Previously this was gated by SPORK_9 which was off on test networks;
after spork removal the check would run unconditionally, requiring
full masternode sync on test networks at superblock heights.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: UdjinM6

doc/release-notes-7278.md

@@ -13,3 +13,7 @@ Updated RPCs
 
 * `getblocktemplate` now always reports `superblocks_enabled` as `true`. The
   field is retained for backwards compatibility.
+
+* `getblocktemplate` now requires a fully synced node at superblock heights.
+  This check is skipped on test networks. Previously it was gated by
+  `SPORK_9_SUPERBLOCKS_ENABLED` which was already always active on mainnet.

src/rpc/mining.cpp

@@ -727,11 +727,11 @@ static RPCHelpMan getblocktemplate()
         if (active_chainstate.IsInitialBlockDownload()) {
             throw JSONRPCError(RPC_CLIENT_IN_INITIAL_DOWNLOAD, PACKAGE_NAME " is in initial sync and waiting for blocks...");
         }
-    }
 
-    if (!node.mn_sync->IsSynced() && CSuperblock::IsValidBlockHeight(active_chain.Height() + 1)) {
-        // Next block is a superblock but we need governance info to correctly construct it.
-        throw JSONRPCError(RPC_CLIENT_IN_INITIAL_DOWNLOAD, PACKAGE_NAME " is syncing with network...");
+        if (!node.mn_sync->IsSynced() && CSuperblock::IsValidBlockHeight(active_chain.Height() + 1)) {
+            // Next block is a superblock but we need governance info to correctly construct it.
+            throw JSONRPCError(RPC_CLIENT_IN_INITIAL_DOWNLOAD, PACKAGE_NAME " is syncing with network...");
+        }
     }
 
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