Add a warning to the atrace binary for deprecating vendor categories

The atrace HAL will be deprecated soon, so vendors will no longer use
it to provide atrace vendor defined categories.
Perfetto will be the tool to replace atrace for that need.
This commit it an attempt to give users a heads up (and maybe help us
find those users).

Test: build and use atrace on Cuttlefish
Bug: 204935495
Change-Id: I9f054e6b07e66d63456d40390fd59ab0913e5f43