Fix bug in AUCPR

The previous commit independently also solves the bug of negative aucpr.
This commit makes two inequalities consistent with eachother when
encountering a 0.0 probability (which should not happen anymore).

Co-Authored-By: Jacob Sznajdman <[email protected]>

Author: Mats-SX

alpha/alpha-algo/src/main/java/org/neo4j/gds/ml/linkmodels/metrics/LinkMetric.java

@@ -80,7 +80,7 @@ void accept(double signedProbability) {
                 }
             }
             lastThreshold = Math.abs(signedProbability);
-            if (signedProbability >= 0) {
+            if (signedProbability > 0) {
                 positivesSeen++;
             } else {
                 negativesSeen++;