MDL-75923 tool_usertours: Update tour content to match formatted content

When an HTML content area contains invalid HTML, some editors will clean
and validate the content upon submission.

In this case the content was:

    <b>Test content</b>

But this should be wrapped in some form of container which accepts
phrasing content (such as a <p> tag).

Some editors, such as TinyMCE, will normalise the content and add the
wrapping paragraph tags to it.

Furthermore, the bold tag is purely stylistic and does not have semantic
meaning. As a result, the <strong> tag is favoured and some editors,
again such as TinyMCE, will replace bold tags with strong tags.

We should update the content here to be valid HTML (wrap the bold tag
in a para), and use a strong tag rather than bold. This allows this test
to pass both with Atto, and other stricter editors such as TinyMCE 6.

admin/tool/usertours/tests/behat/tour_content_type.feature

@@ -58,7 +58,7 @@ Feature: Apply content type to a tour
     And I click on "New step" "link"
     And I set the field "Title" to "tour_activityinfo_course_teacher_title,tool_usertours"
     And I select "Manual" from the "Content type" singleselect
-    And I set the field "id_content" to "<b>Test content</b>"
+    And I set the field "id_content" to "<p><strong>Test content</strong></p>"
     And I press "Save changes"
     And I should see "New: Activity information"
     And I should see "Test content"
@@ -66,7 +66,7 @@ Feature: Apply content type to a tour
     And I should see "Editing \"New: Activity information\""
     And I should not see "Language string ID" in the "#fitem_id_contentlangstring" "css_element"
     And the field "Title" matches value "tour_activityinfo_course_teacher_title,tool_usertours"
-    And the field "id_content" matches value "<b>Test content</b>"
+    And the field "id_content" matches value "<p><strong>Test content</strong></p>"
 
   @javascript
   Scenario: Tour name and description can be translatable