test runner: avoid spawning progress thread when instrumented

because it causes unwanted concurrent accesses to pc tracking

lib/compiler/test_runner.zig

@@ -166,7 +166,7 @@ fn mainTerminal() void {
     var skip_count: usize = 0;
     var fail_count: usize = 0;
     var fuzz_count: usize = 0;
-    const root_node = std.Progress.start(.{
+    const root_node = if (builtin.fuzz) std.Progress.Node.none else std.Progress.start(.{
         .root_name = "Test",
         .estimated_total_items = test_fn_list.len,
     });