Fix web pattern propagation

Fix web pattern propagation

Adding additional "contextPath" to URL patterns caused its doubling.
For instance, the pattern "apidoc/openapi3/apis/single" was represented
as "/apidoc/apidoc/openapi3/apis/single".

New whiteboard implementation adds this "contextPath" automatically,
because of its specification in the constant
HttpWhiteboardConstants.HTTP_WHITEBOARD_CONTEXT_PATH.
This is the difference against older pax-web implementation.

JIRA: AAA-230
Change-Id: I969706594f8cae10781d7a251cc689454982b83e
Signed-off-by: Ivan Martiniak <ivan.martiniak@pantheon.tech>
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>