Build/Test Tools: Add sys_get_temp_dir() to open_basedir tests.

In PHPUnit 10.3.5, 9.6.13 and 8.5.34, the child processes used for process isolation now use temporary files to communicate their result to the parent process.

This caused a failure in some tests that set the `open_basedir` PHP directive to a value that did not include `sys_get_temp_dir()`.

This adds `sys_get_temp_dir()` to the `open_basedir` value set by the tests to ensure that permission is still granted for the temporary directory.

PHPUnit uses `sys_get_temp_dir()`. To ensure the result is the same, Core's `get_temp_dir()` function is not used.

References:
- https://github.com/sebastianbergmann/phpunit/issues/5356

Props desrosj, mukesh27, SergeyBiryukov, costdev.
Merges [56622] to the 6.3 branch.
See #59394.
Built from https://develop.svn.wordpress.org/branches/6.3@56624


git-svn-id: http://core.svn.wordpress.org/branches/6.3@56136 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.3.2-alpha-56582';
+$wp_version = '6.3.2-alpha-56624';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.