regrtest: log timeout at startup (GH-19514)

Reduce also worker timeout.
diff --git a/Lib/test/libregrtest/main.py b/Lib/test/libregrtest/main.py
index 1de51b7..95b4856 100644
--- a/Lib/test/libregrtest/main.py
+++ b/Lib/test/libregrtest/main.py
@@ -394,7 +394,10 @@
 
         save_modules = sys.modules.keys()
 
-        self.log("Run tests sequentially")
+        msg = "Run tests sequentially"
+        if self.ns.timeout:
+            msg += " (timeout: %s)" % format_duration(self.ns.timeout)
+        self.log(msg)
 
         previous_test = None
         for test_index, test_name in enumerate(self.tests, 1):