Add a "make test-rust" target to run the rust tests only.

changes/ticket25071

@@ -0,0 +1,4 @@
+  o Minor features (testing):
+    - Add a "make test-rust" target to run the rust tests only.
+      Closes ticket 25071.
+

src/test/include.am

@@ -358,3 +358,5 @@ EXTRA_DIST += \
 	src/test/test_workqueue_pipe2.sh \
 	src/test/test_workqueue_socketpair.sh
 
+test-rust:
+	$(TESTS_ENVIRONMENT) $(abs_top_srcdir)/src/test/test_rust.sh