[amp-story] ❄️ Fix visual diff flake (#33395)

* fix visual diff

* grid layer

* reset grid layer templates

examples/visual-tests/amp-story/amp-story-bot-rendering.html

@@ -5,11 +5,10 @@
     <script async src="https://cdn.ampproject.org/v0.js"></script>
     <script async custom-element="amp-story" src="https://cdn.ampproject.org/v0/amp-story-1.0.js"></script>
     <script async custom-element="amp-social-share" src="https://cdn.ampproject.org/v0/amp-social-share-0.1.js"></script>
-    <link href='https://fonts.googleapis.com/css?family=Georgia|Open+Sans|Roboto' rel='stylesheet' type='text/css'>
-    <link href="https://fonts.googleapis.com/css?family=Roboto+Condensed" rel="stylesheet">
-    <title>Landscape story</title>
+    <script async custom-element="amp-video" src="https://cdn.ampproject.org/v0/amp-video-0.1.js"></script>
+    <title>Bot rendering</title>
     <meta name="viewport" content="width=device-width,minimum-scale=1,initial-scale=1">
-    <link rel="canonical" href="index.html">
+    <link rel="canonical" href="amp-story-bot-rendering.html">
     <style amp-boilerplate>body{-webkit-animation:-amp-start 8s steps(1,end) 0s 1 normal both;-moz-animation:-amp-start 8s steps(1,end) 0s 1 normal both;-ms-animation:-amp-start 8s steps(1,end) 0s 1 normal both;animation:-amp-start 8s steps(1,end) 0s 1 normal both}@-webkit-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-moz-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-ms-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-o-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}</style><noscript><style amp-boilerplate>body{-webkit-animation:none;-moz-animation:none;-ms-animation:none;animation:none}</style></noscript>
     <style amp-custom>
       body {
@@ -68,7 +67,7 @@
         <amp-story-grid-layer template="fill">
           <amp-img layout="fill" src="./img/cat2.jpg"></amp-img>
         </amp-story-grid-layer>
-        <amp-story-grid-layer template="center">
+        <amp-story-grid-layer template="vertical">
           <p>
             <span data-text-background-color="crimson">i can fit in that box but inspect anything brought into the house wack the mini furry mouse intently stare at the same spot. Flee in terror at cucumber discovered on floor shake treat bag</span>
           </p>
@@ -80,7 +79,7 @@
         <amp-story-grid-layer template="fill">
           <amp-img layout="fill" src="./img/cat2.jpg"></amp-img>
         </amp-story-grid-layer>
-        <amp-story-grid-layer template="center">
+        <amp-story-grid-layer template="vertical">
           <p>
             <span data-text-background-color="crimson">i can fit in that box but inspect anything brought into the house wack the mini furry mouse intently stare at the same spot. Flee in terror at cucumber discovered on floor shake treat bag</span>
           </p>