Move the test template to //testing/test.gni (part 2)

tools/gn/format_test_data/030.gn

 # Don't separate simple statements in a scope.
+
+import("//testing/rules.gni")
+
 test("something") {
   if (is_linux) {
     sources -= [ "file_version_info_unittest.cc" ]
     sources += [ "nix/xdg_util_unittest.cc" ]
     defines = [ "USE_SYMBOLIZE" ]
     configs += [ "//build/config/linux:glib" ]
   }
 }