Fix system test scaffold generator for vowels

Fix issue where running "rails g scaffold Author" will create system
test names like "creating a Author" and "updating a Author" so that
there are not grammatical errors. Now running "rails g scaffold Author"
will generate "should create Author", "should update Author", and
"should destroy Author" which works around the article vowel-sound
agreement issues.

Fixes #40744

guides/source/testing.md

@@ -864,7 +864,7 @@ You can also run `bin/rails test:all` to run all tests, including system tests.
 Now let's test the flow for creating a new article in our blog.
 
 ```ruby
-test "creating an article" do
+test "should create Article" do
   visit articles_path
 
   click_on "New Article"

railties/CHANGELOG.md

@@ -1,3 +1,11 @@
+*   Modified scaffold generator template so that running
+    `rails g scaffold Author` no longer generates tests called "creating
+    a Author", "updating a Author", and "destroying a Author"
+
+    Fixes #40744.
+
+    *Michael Duchemin*
+
 *   Add benchmark method that can be called from anywhere.
 
     This method is used as a quick way to measure & log the speed of some code.

railties/lib/rails/generators/test_unit/scaffold/templates/system_test.rb.tt

@@ -11,7 +11,7 @@ class <%= class_name.pluralize %>Test < ApplicationSystemTestCase
     assert_selector "h1", text: "<%= class_name.pluralize.titleize %>"
   end
 
-  test "creating a <%= human_name %>" do
+  test "should create <%= human_name %>" do
     visit <%= plural_table_name %>_url
     click_on "New <%= class_name.titleize %>"
 
@@ -28,7 +28,7 @@ class <%= class_name.pluralize %>Test < ApplicationSystemTestCase
     click_on "Back"
   end
 
-  test "updating a <%= human_name %>" do
+  test "should update <%= human_name %>" do
     visit <%= plural_table_name %>_url
     click_on "Edit", match: :first
 
@@ -45,7 +45,7 @@ class <%= class_name.pluralize %>Test < ApplicationSystemTestCase
     click_on "Back"
   end
 
-  test "destroying a <%= human_name %>" do
+  test "should destroy <%= human_name %>" do
     visit <%= plural_table_name %>_url
     page.accept_confirm do
       click_on "Destroy", match: :first