chore: do not load Lumo CSS in dev pages by default (#9997)

Author: web-padawan

dev/accordion.html

@@ -5,7 +5,6 @@
     <meta http-equiv="X-UA-Compatible" content="IE=edge" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>Accordion</title>
-    <link rel="stylesheet" href="/packages/vaadin-lumo-styles/lumo.css" />
     <script type="module" src="./common.js"></script>
 
     <script type="module">

dev/app-layout.html

@@ -9,7 +9,6 @@
     <!-- possible content values: default, black or black-translucent -->
     <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent" />
     <title>App Layout</title>
-    <link rel="stylesheet" href="/packages/vaadin-lumo-styles/lumo.css" />
     <script type="module" src="./common.js"></script>
 
     <style>

dev/avatar-group.html

@@ -5,7 +5,6 @@
     <meta http-equiv="X-UA-Compatible" content="IE=edge" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>Avatar Group</title>
-    <link rel="stylesheet" href="/packages/vaadin-lumo-styles/lumo.css" />
     <script type="module" src="./common.js"></script>
 
     <script type="module">

dev/avatar.html

@@ -5,7 +5,6 @@
     <meta http-equiv="X-UA-Compatible" content="IE=edge" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>Avatar</title>
-    <link rel="stylesheet" href="/packages/vaadin-lumo-styles/lumo.css" />
     <script type="module" src="./common.js"></script>
 
     <script type="module">

dev/button.html

@@ -5,7 +5,6 @@
     <meta http-equiv="X-UA-Compatible" content="IE=edge" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>Button</title>
-    <link rel="stylesheet" href="/packages/vaadin-lumo-styles/lumo.css" />
     <script type="module" src="./common.js"></script>
 
     <script type="module">

dev/card.html

@@ -5,7 +5,6 @@
     <meta http-equiv="X-UA-Compatible" content="IE=edge" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>Card</title>
-    <link rel="stylesheet" href="/packages/vaadin-lumo-styles/lumo.css" />
     <script type="module" src="./common.js"></script>
 
     <script type="module">

dev/charts/area.html

@@ -4,7 +4,6 @@
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>Vaadin charts | area</title>
-    <link rel="stylesheet" href="/packages/vaadin-lumo-styles/lumo.css" />
     <script type="module" src="../common.js"></script>
     <script type="module">
       import '@vaadin/charts';

dev/charts/arearange.html

@@ -12,7 +12,6 @@
           series.values = data;
         });
     </script>
-    <link rel="stylesheet" href="/packages/vaadin-lumo-styles/lumo.css" />
     <script type="module" src="../common.js"></script>
     <script type="module">
       import '@vaadin/charts';

dev/charts/areaspline.html

@@ -4,7 +4,6 @@
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>Vaadin charts | area spline</title>
-    <link rel="stylesheet" href="/packages/vaadin-lumo-styles/lumo.css" />
     <script type="module" src="../common.js"></script>
     <script type="module">
       import '@vaadin/charts';

dev/charts/areasplinerange.html

@@ -4,7 +4,6 @@
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>Vaadin charts | area spline range</title>
-    <link rel="stylesheet" href="/packages/vaadin-lumo-styles/lumo.css" />
     <script type="module" src="../common.js"></script>
     <script type="module">
       import '@vaadin/charts';