Issue #3035318 by mpdonadio: `DateFormatter()` assumes 30 days per month,...

Issue #3035318 by mpdonadio: `DateFormatter()` assumes 30 days per month, while February only has 28 days.  Causes fails in tests

core/modules/datetime/tests/src/Functional/DateTimeTimeAgoFormatterTest.php

@@ -110,13 +110,13 @@ public function testSettings() {
     $edit = [
       'fields[field_datetime][settings_edit_form][settings][future_format]' => 'ends in @interval',
       'fields[field_datetime][settings_edit_form][settings][past_format]' => 'started @interval ago',
-      'fields[field_datetime][settings_edit_form][settings][granularity]' => 3,
+      'fields[field_datetime][settings_edit_form][settings][granularity]' => 1,
     ];
     $this->drupalPostForm(NULL, $edit, 'Update');
     $this->drupalPostForm(NULL, [], 'Save');
 
-    $this->assertSession()->pageTextContains('ends in 1 year 1 month 1 week');
-    $this->assertSession()->pageTextContains('started 1 year 1 month 1 week ago');
+    $this->assertSession()->pageTextContains('ends in 1 year');
+    $this->assertSession()->pageTextContains('started 1 year ago');
   }
 
 }

core/tests/Drupal/FunctionalTests/Datetime/TimestampAgoFormatterTest.php

@@ -110,13 +110,13 @@ public function testSettings() {
     $edit = [
       'fields[field_timestamp][settings_edit_form][settings][future_format]' => 'ends in @interval',
       'fields[field_timestamp][settings_edit_form][settings][past_format]' => 'started @interval ago',
-      'fields[field_timestamp][settings_edit_form][settings][granularity]' => 3,
+      'fields[field_timestamp][settings_edit_form][settings][granularity]' => 1,
     ];
     $this->drupalPostForm(NULL, $edit, 'Update');
     $this->drupalPostForm(NULL, [], 'Save');
 
-    $this->assertSession()->pageTextContains('ends in 1 year 1 month 1 week');
-    $this->assertSession()->pageTextContains('started 1 year 1 month 1 week ago');
+    $this->assertSession()->pageTextContains('ends in 1 year');
+    $this->assertSession()->pageTextContains('started 1 year ago');
   }
 
 }