Fix service matching logic to use contains instead of exact match

The service discovery was using exact equality (==) instead of contains
matching, preventing services like 'sshd' from matching the 'sshd' pattern.
Restore original contains-based matching logic to find configured services.

agent/src/collectors/systemd.rs

@@ -196,7 +196,7 @@ impl SystemdCollector {
 
                 // Check if this service matches our filter patterns
                 for pattern in service_name_filters {
-                    if service_name == pattern {
+                    if service_name.contains(pattern) || pattern.contains(service_name) {
                         debug!(
                             "INCLUDING service '{}' because it matches pattern '{}'",
                             service_name, pattern