[Arista] Remove arista.log from rsyslog default logrotate (#9731)

Why I did it
In parallel of this change Arista added a custom logrotate configuration as part of its driver library.
Having 2 logrotate configuration for the same log file triggers an issue.

Fixes aristanetworks/sonic#38

How I did it
Arista merged a few changes in sonic-buildimage which added a logrotate configuration aristanetworks/sonic@e43c797
It is therefore the right path to remove the arista.log line from the logrotate.d/rsyslog configuration.

How to verify it
Logrotate works without any error message, arista log rotation happens and arista daemons still append logs once file was truncated.

Author: Staphylo

files/image_config/logrotate/rsyslog.j2

@@ -24,7 +24,6 @@
 }
 
 /var/log/auth.log
-/var/log/arista.log
 /var/log/cron.log
 /var/log/syslog
 /var/log/teamd.log