oe_syslog.py: fix settings in OEHasPackage decorator
1. For test_syslog_running, we should not restrict it to run for
only busybox-syslog and sysklogd. So extend it to all syslog
providers in oe-core and meta-openembedded.
2. For test_syslog_startup_config, fix to make it depend on the
existence of busybox-syslog. The previous condition "!sysklogd
&& busybox" is incorrect, because busybox may be compiled without
syslog support, and sysklogd and busybox-syslog conflict with
each other.
