fix(build): Use build/msg/en.js instead of msg/messages.js in tests

This has no direct effect but fixes a long-standing misdesign
where we are testing against the input to, rather than the output
of, the language file processing pipeline.

tests/bootstrap.js

@@ -96,7 +96,7 @@
     // whether Blockly is loaded from compressed or uncompressed.
     // Paths relative to root.
     additionalScripts: [
-      'msg/messages.js',
+      'build/msg/en.js',
     ],
   };
   if (typeof window.BLOCKLY_BOOTSTRAP_OPTIONS === 'object') {

tests/compile/index.html

@@ -4,7 +4,7 @@
   <meta charset="utf-8">
   <title>Blockly: Advanced Compilation Test</title>
   <script src="main_compressed.js"></script>
-  <script src="../../msg/js/en.js"></script>
+  <script src="../../build/msg/en.js"></script>
   <style>
     body {
       background-color: #fff;

tests/generators/index.html

@@ -6,7 +6,7 @@
 <script>
   var BLOCKLY_BOOTSTRAP_OPTIONS = {
     additionalScripts: [
-      'msg/messages.js',
+      'build/msg/en.js',
       'tests/generators/unittest_javascript.js',
       'tests/generators/unittest_python.js',
       'tests/generators/unittest_php.js',

tests/mocha/index.html

@@ -112,7 +112,7 @@
           'Blockly.test.zoomControls',
         ],
         additionalScripts: [
-          'msg/messages.js',
+          'build/msg/en.js',
           'tests/playgrounds/screenshot.js',
           'node_modules/@blockly/dev-tools/dist/index.js',
         ],

tests/playground.html

@@ -9,7 +9,7 @@
 <script>
   var BLOCKLY_BOOTSTRAP_OPTIONS = {
     additionalScripts: [
-      'msg/messages.js',
+      'build/msg/en.js',
       'tests/playgrounds/screenshot.js',
       'node_modules/@blockly/dev-tools/dist/index.js',
     ],

tests/playgrounds/advanced_playground.html

@@ -7,7 +7,7 @@
 <script>
   var BLOCKLY_BOOTSTRAP_OPTIONS = {
     additionalScripts: [
-      'msg/messages.js',
+      'build/msg/en.js',
       'tests/playgrounds/screenshot.js',
       'tests/themes/test_themes.js',
       'node_modules/@blockly/dev-tools/dist/index.js',