Replace usages of AssertLegacyTrait::assertPattern, that is deprecated

Adding the "Deprecated assertions" tag to add this into the kanban board https://contribkanban.com/board/Deprecatedassertions

1. +++ b/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
   @@ -284,6 +284,17 @@ public function testTextAsserts() {
   +  public function testAssertPattern() {
   +    $this->drupalGet('test-escaped-characters');
   +    $this->assertPattern('/div class.*escaped/');
   

   Deprecated AssertLegacyTrait::assertPattern() gets tested

2. +++ b/core/tests/Drupal/Tests/Listeners/DeprecationListenerTrait.php
   @@ -185,7 +185,6 @@ public static function getSkippedDeprecations() {
   -      'AssertLegacyTrait::assertPattern() is deprecated in drupal:8.2.0 and is removed from drupal:10.0.0. Use $this->assertSession()->responseMatches() instead. See https://www.drupal.org/node/3129738',
   

   Removed from the list.

3. Testing passed -- no more left to replace
4. No CS violations

It's ready to go to me, Thanks @mondrake!

core/tests/Drupal/KernelTests/AssertContentTrait.php has a non-deprecated version of assertPattern(). What's up, doc?

Thanks/sorry,
-Derek

Re #14: thanks for clarifying.
#12 is an excellent RTBC. ;) That's everything I just checked and agree with all points.

One might complain that the summary is a bit bare, but this is part of a bigger effort and it says all it needs to say. ;)

Thanks/sorry,
-Derek

Random fail. Requeued.

Needs a re-roll.

Rejected:

$ cat core/tests/Drupal/Tests/Listeners/DeprecationListenerTrait.php.rej
diff a/core/tests/Drupal/Tests/Listeners/DeprecationListenerTrait.php b/core/tests/Drupal/Tests/Listeners/DeprecationListenerTrait.php  (rejected hunks)
@@ -185,7 +185,6 @@ public static function getSkippedDeprecations() {
       'AssertLegacyTrait::assertFieldsByValue() is deprecated in drupal:8.3.0 and is removed from drupal:10.0.0. Use iteration over the fields yourself instead and directly check the values in the test. See https://www.drupal.org/node/3129738',
       'AssertLegacyTrait::assertEscaped() is deprecated in drupal:8.2.0 and is removed from drupal:10.0.0. Use $this->assertSession()->assertEscaped() instead. See https://www.drupal.org/node/3129738',
       'AssertLegacyTrait::assertNoEscaped() is deprecated in drupal:8.2.0 and is removed from drupal:10.0.0. Use $this->assertSession()->assertNoEscaped() instead. See https://www.drupal.org/node/3129738',
-      'AssertLegacyTrait::assertPattern() is deprecated in drupal:8.2.0 and is removed from drupal:10.0.0. Use $this->assertSession()->responseMatches() instead. See https://www.drupal.org/node/3129738',
       'AssertLegacyTrait::constructFieldXpath() is deprecated in drupal:8.5.0 and is removed from drupal:10.0.0. Use $this->getSession()->getPage()->findField() instead. See https://www.drupal.org/node/3129738',
     ];
   }

rawdiff looks good. Only context changed, nothing in the code.
Confirming #19 applies cleanly to 9.1.x branch.
Assuming the bot is happy, this is RTBC again.

Thanks,
-Derek

Committed 49d9b09 and pushed to 9.1.x. Thanks!