Use has.add for config-useDeferredInstrumentation

This ensures that a default build works the same as an unbuilt
version of Dojo, while still allowing the configuration value
to be fixed during a build.

Fixes #17753.

(cherry picked from commit fdcc15e86445ea8b893ef65d29b860ef12a2abb3)
(cherry picked from commit 5b28811930e9353160fe7f0a9680615e3da98639)