[roll] Roll fuchsia [bazel_sdk][versioning] Update default_fuchsia_api_level to supported level 16

The previous value, 15, was retired months ago.

Also explain why the drivers tests cannot use the default API level.

Original-Bug: 354047162, 382560521
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1170003
Original-Revision: e60ae649d3e841967ada4fb31ee253cf7aecaef8
GitOrigin-RevId: 42d4a0c7c19e42bd44abf9790f29579c8d3115b6
Change-Id: Ibfffbfe808bd6ecb770a73d71ddd101da8518f61

Author: David Dorwin

stem

@@ -11,7 +11,7 @@
              githooks="integration/git-hooks"
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="0ae08c07324f467ac81fec0d84adf46e1f052e9b"/>
+             revision="e60ae649d3e841967ada4fb31ee253cf7aecaef8"/>
   </projects>
   <hooks>
     <hook name="install-environment"