system_server: clean up stale rules

979adffd added an auditallow
to see if system_server was relabeling system_data_file.
The auditallow rule hasn't triggered, so remove the allow rule.

a3c97a76 added an auditallow
to see if system_server was executing toolbox. The auditallow
rule hasn't triggered, so remove the allow rule. AFAIK,
system_server never executes ANY file, so further tightening here
is feasible.

Change-Id: Ia0a93f3833e32c3e2c898463bd8813701a6dd20a