refactor: Clamp worker threads in ChainstateManager constructor

This ensures the options are applied consistently from contexts where
they might not pass through the args manager, such as in some tests, or
when used through the kernel library.

This is similar to the patch applied in 09ef322acc.

src/node/chainstatemanager_args.cpp

@@ -60,8 +60,7 @@ util::Result<void> ApplyArgsManOptions(const ArgsManager& args, ChainstateManage
         script_threads += GetNumCores();
     }
     // Subtract 1 because the main thread counts towards the par threads.
-    opts.worker_threads_num = std::clamp(script_threads - 1, 0, MAX_SCRIPTCHECK_THREADS);
-    LogPrintf("Script verification uses %d additional threads\n", opts.worker_threads_num);
+    opts.worker_threads_num = script_threads - 1;
 
     if (auto max_size = args.GetIntArg("-maxsigcachesize")) {
         // 1. When supplied with a max_size of 0, both the signature cache and

src/node/chainstatemanager_args.h

@@ -10,8 +10,6 @@
 
 class ArgsManager;
 
-/** Maximum number of dedicated script-checking threads allowed */
-static constexpr int MAX_SCRIPTCHECK_THREADS{15};
 /** -par default (number of script-checking threads, 0 = auto) */
 static constexpr int DEFAULT_SCRIPTCHECK_THREADS{0};