testing: Globally define logging via syslog for charon-systemd

We could make the same change for charon (actually setting it for charon
in strongswan.conf.testing would work for charon-systemd too), however,
there are dozens of test cases that currently set charondebug in
ipsec.conf.

testing/tests/sql/ip-split-pools-db/hosts/carol/etc/strongswan.conf

@@ -1,14 +1,6 @@
 # /etc/strongswan.conf - strongSwan configuration file
 
 charon {
-  syslog {
-    daemon {
-      default = 1
-    }
-    auth {
-      default = 0
-    }
-  }
   plugins {
     sql {
       database = sqlite:///etc/db.d/ipsec.db

testing/tests/sql/ip-split-pools-db/hosts/dave/etc/strongswan.conf

@@ -1,14 +1,6 @@
 # /etc/strongswan.conf - strongSwan configuration file
 
 charon {
-  syslog {
-    daemon {
-      default = 1
-    }
-    auth {
-      default = 0
-    }
-  }
   plugins {
     sql {
       database = sqlite:///etc/db.d/ipsec.db

testing/tests/sql/ip-split-pools-db/hosts/moon/etc/strongswan.conf

@@ -3,14 +3,6 @@
 charon {
   load = random nonce aes sha1 sha2 pem pkcs1 gmp x509 curl revocation hmac vici kernel-netlink socket-default updown sqlite sql attr-sql
 
-  syslog {
-    daemon {
-      default = 1
-    }
-    auth {
-      default = 0
-    }
-  }
   plugins {
     sql {
       database = sqlite:///etc/db.d/ipsec.db