Update supported-as-values.html: json should not be supported (#45426)

Author: noamr

preload/supported-as-values.html

@@ -7,7 +7,6 @@
 <meta name="variant" content="?as=font&expected=1">
 <meta name="variant" content="?as=script&expected=1">
 <meta name="variant" content="?as=style&expected=1">
-<meta name="variant" content="?as=json&expected=1">
 <meta name="variant" content="?as=track&expected=1">
 
 <meta name="variant" content="?as=garbagefoobar&expected=0">
@@ -16,6 +15,7 @@
 <meta name="variant" content="?as=object&expected=0">
 <meta name="variant" content="?as=iframe&expected=0">
 <meta name="variant" content="?as=worklet&expected=0">
+<meta name="variant" content="?as=json&expected=0">
 
 <script src="/common/utils.js"></script>
 <script src="/resources/testharness.js"></script>