ceph.spec.in: cleanup sysctl_apply check

sysctl_apply macro is supported on systemd since v215 [1].
This macro should be supported from Centos 7.2 and above, since we use
C9 to build (and 8 is EOL) - we can cleanup this check.

[1] systemd/systemd@b532bde

Signed-off-by: Matan Breizman <[email protected]>

Author: Matan-B

ceph.spec.in

@@ -2340,11 +2340,7 @@ fi
 if [ $1 -eq 1 ] ; then
 /usr/bin/systemctl start ceph-osd.target >/dev/null 2>&1 || :
 fi
-%if 0%{?sysctl_apply}
-    %sysctl_apply 90-ceph-osd.conf
-%else
-    /usr/lib/systemd/systemd-sysctl %{_sysctldir}/90-ceph-osd.conf > /dev/null 2>&1 || :
-%endif
+%sysctl_apply 90-ceph-osd.conf
 
 %preun osd
 %if 0%{?suse_version}