[sestarnix] Report extended_socket_class support correctly

All currently supported socket types affected by the extended
socket class policy capability are now appropriately labeled, so
update the reported support level.

Bug: 398699131
Change-Id: I6d962e6a441dfca04f35d4a9136407679e9d1d19
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1497740
Commit-Queue: Wez <wez@google.com>
Reviewed-by: Ambre Williams <ambre@google.com>
Fuchsia-Auto-Submit: Wez <wez@google.com>