Update recompute method and rename test case.

Signed-off-by: Arthur Schreiber <arthurschreiber@github.com>

go/vt/discovery/healthcheck.go

@@ -603,13 +603,20 @@ func (hc *HealthCheckImpl) recomputeHealthy(key KeyspaceShardTabletType) {
 // Recompute the healthy primary tablet for the given key.
 func (hc *HealthCheckImpl) recomputeHealthyPrimary(key KeyspaceShardTabletType) {
 	highestPrimaryTermStartTime := int64(math.MinInt64)
+	var newestPrimary *TabletHealth
 
 	for _, s := range hc.healthData[key] {
 		if s.PrimaryTermStartTime >= highestPrimaryTermStartTime {
 			highestPrimaryTermStartTime = s.PrimaryTermStartTime
-			hc.healthy[key][0] = s
+			newestPrimary = s
 		}
 	}
+
+	if newestPrimary != nil {
+		hc.healthy[key] = []*TabletHealth{newestPrimary}
+	} else {
+		hc.healthy[key] = []*TabletHealth{}
+	}
 }
 
 // Subscribe adds a listener. Used by vtgate buffer to learn about primary changes.

go/vt/discovery/healthcheck_test.go

@@ -857,7 +857,7 @@ func TestRemoveTablet(t *testing.T) {
 //
 // During this time, operations like `RemoveTablet` should not lead
 // to multiple tablets becoming valid targets for `PRIMARY`.
-func TestTabletRemoveDuringExternalReparenting(t *testing.T) {
+func TestRemoveTabletDuringExternalReparenting(t *testing.T) {
 	ctx := utils.LeakCheckContext(t)
 
 	// reset error counters