Refactor uploads preview error banner to use a shared component

Also refactor a corresponding test to avoid asserting on the content

app/templates/partials/check/letter-too-long.html

@@ -1,4 +1,4 @@
-<h1 class='banner-title' data-module="track-error" data-error-type="Trying to send a letter that's too long" data-error-label="{{ upload_id }}">
+<h1 class='banner-title' data-module="track-error" data-error-type="Trying to send a letter that's too long" data-error-label="service_id: {{ current_service.id }}">
   Your letter is too long
 </h1>
 <p>

app/templates/partials/check/letter-validation-failed-banner.html

@@ -2,9 +2,13 @@
 
 {% call banner_wrapper(type='dangerous') %}
   {% if message is string %}
-    <h1 class="banner-title">{{ message }}</h1>
+    <h1 class="banner-title">
+      {{ message }}
+    </h1>
   {% else %}
-    <h1 class="banner-title">{{ message.title }}</h1>
+    <h1 class="banner-title" data-module="track-error" data-error-type="{{ error_code }}" data-error-label="precompiled letter validation failed for service_id: {{ current_service.id }}">
+      {{ message.title }}
+    </h1>
     {% if message.detail %}
       <p>
         {{ message.detail | safe }}

app/templates/views/uploads/preview.html

@@ -9,13 +9,8 @@
 {% endblock %}
 
 {% block maincolumn_content %}
-  {% if status == 'invalid' and error %}
-    {% call banner_wrapper(type='dangerous') %}
-      <h1 class="banner-title">{{ error.title }}</h1>
-      {% if error.detail %}
-        <p>{{ error.detail | safe }}</p>
-      {% endif %}
-    {% endcall %}
+  {% if status == 'invalid' and message %}
+    {% include "partials/check/letter-validation-failed-banner.html" %}
   {% elif current_service.trial_mode %}
     {% call banner_wrapper(type='dangerous') %}
       {% with