The search tests have a bunch of test cases that were querying URLs

based on the local_id field. For some of these, the test is checking

that a review request on the global site does not show up when searching

within a local site. In these cases, the local_id field can be None,

which now causes a reverse lookup error (before it ended up just

sticking "None" in for the ID, which used to give us a URL but didn't

make sense).
I've changed all the test cases to instead use the display_id field

when creating API URLs within the tests.

Ran unit tests.