MDL-81455 core: Fix welcome message heading in dashboard

The welcome message on login was incorrectly replacing the dashboard
page header.The change ensures the welcome message appears as a
paragraph while maintaining the dashboard page heading.

lib/templates/full_header.mustache

@@ -45,19 +45,21 @@
             </div>
         </div>
         <div class="d-flex align-items-center">
-            {{^welcomemessage}}
+            <div class="me-auto d-flex flex-column">
                 {{#contextheader}}
-                    <div class="me-auto">
-                        {{{contextheader}}}
-                    </div>
+                <div>
+                    {{{contextheader}}}
+                </div>
                 {{/contextheader}}
-            {{/welcomemessage}}
-            {{> core/welcome }}
+                <div>
+                    {{> core/welcome }}
+                </div>
+            </div>
             <div class="header-actions-container ms-auto" data-region="header-actions-container">
                 {{#headeractions}}
-                    <div class="header-action ms-2">{{{.}}}</div>
+                <div class="header-action ms-2">{{{.}}}</div>
                 {{/headeractions}}
             </div>
         </div>
     </div>
-</header>
+</header>

lib/templates/welcome.mustache

@@ -25,7 +25,7 @@
     }
 }}
 {{#welcomemessage}}
-<h1 class="h2 mb-3 mt-3">
-    {{.}}
-</h1>
-{{/welcomemessage}}
+<div class="mb-2">
+    <span class="h2">{{.}}</span>
+</div>
+{{/welcomemessage}}

theme/boost/tests/behat/welcome_to_moodle.feature

@@ -8,7 +8,7 @@ Feature: Welcome message on boost
     Given the following config values are set as admin:
       | defaulthomepage | 0 |
     When I log in as "admin"
-    Then I should not see "Acceptance test site" in the "page-header" "region"
+    Then I should see "Acceptance test site" in the "page-header" "region"
     And I should see "Welcome, Admin!" in the "page-header" "region"
     And I reload the page
     And I should not see "Welcome, Admin!" in the "page-header" "region"
@@ -18,7 +18,7 @@ Feature: Welcome message on boost
     Given the following config values are set as admin:
       | defaulthomepage | 1 |
     When I log in as "admin"
-    Then I should not see "Dashboard" in the "page-header" "region"
+    Then I should see "Dashboard" in the "page-header" "region"
     And I should see "Welcome, Admin!" in the "page-header" "region"
     And I reload the page
     And I should not see "Welcome, Admin!" in the "page-header" "region"
@@ -28,7 +28,7 @@ Feature: Welcome message on boost
     Given the following config values are set as admin:
       | defaulthomepage | 3 |
     When I log in as "admin"
-    Then I should not see "My courses" in the "page-header" "region"
+    Then I should see "My courses" in the "page-header" "region"
     And I should see "Welcome, Admin!" in the "page-header" "region"
     And I reload the page
     And I should not see "Welcome, Admin!" in the "page-header" "region"