TT#66754 Refactor status gatherer program check into a function

Let's encapsulate the knowledge about ngcp-collective-check into the
same perl module, instead of leaking the implementation details in
multiple places.

Change-Id: I3efe0b9704f9c149dae50bf4d323853b819127c8

lib/NGCP/Panel/Utils/Statistics.pm

@@ -86,6 +86,12 @@ sub get_dpkg_support_status {
     }
 }
 
+sub has_ngcp_status {
+    my $self = shift;
+
+    return -x '/usr/sbin/ngcp-collective-check';
+}
+
 sub get_ngcp_status {
     my ($self) = @_;
     return `/usr/sbin/ngcp-collective-check json`;

lib/NGCP/Panel/Widget/Dashboard/AdminSystemOverview.pm

@@ -8,7 +8,7 @@ use NGCP::Panel::Utils::Statistics;
 use JSON qw(decode_json);
 
 sub template {
-    return unless ( -e '/usr/sbin/ngcp-collective-check' );
+    return unless NGCP::Panel::Utils::Statistics::has_ngcp_status();
     return 'widgets/admin_system_overview.tt';
 }