(REF) Tidy up properties in CRM_Core_ResourcesTest

[braders]

Overview

This is a general tidy up of CRM_Core_ResourcesTest. The driving motivation is removing dynamic properties for PHP8.2 support, but in this case the refactoring goes slightly further.

Before

1. basedir and container existed as dynamic properties. Aside from dynamic properties being deprecated, these properties were not used.
2. _createMapper took $cache and $cacheKey arguments, but nothing that called _createMapper ever passed in a value.
3. I think many people would argue that the use of list was unnecessary here, and harmed readability.

After

Refactored so that the unneccessary dynamic properties are not created, and tidied up the createMapper function.

Comments

As this is a test there should be no backwards-compat risk to changing createMapper.

$this->mapper is only actually referenced in commented out code. I almost went a step further and made $mapper a local variable, not a property, but I was not sure if it was appropriate to delete the commented out test that referenced $this->mapper, or leave the commented out code pointing to a property that no longer exists.

[civibot]

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[braders]

Jenkins re test this please