10_immutable.cf: Use getacls instead of command

Ticket: ENT-10961, CFE-1840
Signed-off-by: Lars Erik Wik <lars.erik.wik@northern.tech>

Author: larsewi

tests/acceptance/10_files/unsafe/10_immutable.cf

@@ -67,17 +67,12 @@ bundle agent test
 bundle agent check
 {
   vars:
-    "getfacl"
-      string => ifelse(
-        fileexists("/var/cfengine/bin/getfacl"), # if
-        "/var/cfengine/bin/getfacl", # then
-        "/usr/bin/getfacl" # else
-      );
-
     "expected"
       string => ".*user:root:rwx.*";
+    "acls"
+      slist => getacls("$(global.filename)", "access");
     "actual"
-      string => execresult("$(getfacl) $(global.testfile)", "noshell");
+      string => nth("acls", "0");
 
   classes:
     "ok"