Tests: Remove `@covers` tags for native PHP functions in `phpunit/tests/compat/`.

As these are not user-defined functions, they cause notices when generating the code coverage report:
{{{
"@covers ::array_key_first" is invalid
"@covers ::array_key_last" is invalid
"@covers ::hash_hmac" is invalid
"@covers ::is_countable" is invalid
"@covers ::is_iterable" is invalid
"@covers ::mb_strlen" is invalid
"@covers ::mb_substr" is invalid
"@covers ::str_contains" is invalid
"@covers ::str_ends_with" is invalid
"@covers ::str_starts_with" is invalid
}}}

Follow-up to [51852], [52038], [52039], [52040].

See #39265, #55652.
Built from https://develop.svn.wordpress.org/trunk@54049


git-svn-id: http://core.svn.wordpress.org/trunk@53608 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.1-alpha-54048';
+$wp_version = '6.1-alpha-54049';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.