QA: increase add topic timeout to 10 seconds

Many, many tests fail sporadically in creating a new topic with
"Element still visible after 5 seconds" because saving sometimes takes
more than the default 5 second timeout.

Bug: 71476
Change-Id: I47b4f1f4c52d486f280188bcbc0a5d2910b9f535
Merge "QA: increase add topic timeout to 10 seconds"