set maximum size of thread pool to 31 (#7290)

cli/tokio_util.rs

@@ -5,6 +5,12 @@ pub fn create_basic_runtime() -> tokio::runtime::Runtime {
     .basic_scheduler()
     .enable_io()
     .enable_time()
+    // This limits the number of threads for blocking operations (like for
+    // synchronous fs ops) or CPU bound tasks like when we run dprint in
+    // parallel for deno fmt.
+    // The default value is 512, which is an unhelpfully large thread pool. We
+    // don't ever want to have more than a couple dozen threads.
+    .max_threads(32)
     .build()
     .unwrap()
 }