add micrometer to collect metrics for prometheus

src/main/java/eu/openaire/api/config/metrics/MetricsAspect.java

@@ -29,7 +29,6 @@ public class MetricsAspect {
     @Around("@annotation(io.micrometer.core.annotation.Timed)")
     public Object timeAnnotatedMethods(ProceedingJoinPoint joinPoint) throws Throwable {
         Method method = ((MethodSignature) joinPoint.getSignature()).getMethod();
-        Timed timed = method.getAnnotation(Timed.class);
 
         String className = joinPoint.getTarget().getClass().getSimpleName();
         String methodName = method.getName();