Emphasize Test Tab is Stateless

When testing APIM, users often set headers, select products, etc. on the _Test_ tab, then switch away to do something else after the test. When coming back to the _Test_ tab, there is an expectation that the test parameters were retained, when, in fact, they are stateless and need to be repopulated. This is a less than ideal situation, and we do not make it very clear in our lab documentation that parameters need to be repopulated.

Look through the parts of the labs where tests are initiated from the APIM Azure Portal and consider refining the language to emphasize the need to repopulate.