aws: Set awsPreferCNAME to true

Prevent the switch of CNAME records to Alias A records for CNAMES with
an aws ec2 loadbalancer as the target.  Prevent evaluate target health
automatically being applied to alias targets (Not strictly required
since we don't create any now but turning it off anyway)

internal/provider/aws/aws.go

@@ -44,8 +44,8 @@ const (
 	providerSpecificGeolocationContinentCode = "aws/geolocation-continent-code"
 	awsBatchChangeSize                       = 1000
 	awsBatchChangeInterval                   = time.Second
-	awsEvaluateTargetHealth                  = true
-	awsPreferCNAME                           = false
+	awsEvaluateTargetHealth                  = false
+	awsPreferCNAME                           = true
 	awsZoneCacheDuration                     = 0 * time.Second
 )