Fix for invalid discovery query in the RE.

Fix for invalid discovery query in the RE.

When do discovery with specific uri using RE layer,
RE layer trigger to find resource with invalid uri
which is specific uri without wellknown-uri(/oic/res).

But, resource server never response for this discovery request.
Because discovery request only handled by /oic/res,
other discovery request does not a handled by base stack.

In this patch,
1) Request uri is changed to wellknown uri.
2) Related unit test is modified.

Change-Id: I529430834f8c48b0eb5e31b6f58da33fb55c946c
Signed-off-by: KIM JungYong <jyong2.kim@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/18191
Tested-by: jenkins-iotivity <jenkins@iotivity.org>
Reviewed-by: Uze Choi <uzchoi@samsung.com>
Tested-by: Uze Choi <uzchoi@samsung.com>