2/2: Rename domain "system" to "system_server".

This CL completes the renaming of domain system to system_server by
removing the "system" typealias that was temporarily added to avoid
breaking the build while the rename CLs are landing.

Change-Id: I05d11571f0e3d639026fcb9341c3476d44c54fca

system_server.te

@@ -7,9 +7,6 @@ permissive system_server;
 unconfined_domain(system_server);
 relabelto_domain(system_server);
 
-# TODO: Remove the temporary alias below once the renaming of system to system_server is complete in all repositories.
-typealias system_server alias system;
-
 # These are the capabilities assigned by the zygote to the
 # system server.
 allow system_server self:capability {