[5.3] Change isset($var) && multiple times to one isset call

[joomdonation]

Pull Request for Issue # .

Summary of Changes

This PR improves code quality of our code base by running PHPCS Fixer for combine_consecutive_issets rule.

Testing Instructions

Code review

Actual result BEFORE applying this Pull Request

Works

Expected result AFTER applying this Pull Request

Works, with cleaner code

Link to documentations

Please select:

• Documentation link for docs.joomla.org:

• No documentation changes for docs.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed

[QuyTon]

I have tested this item ✅ successfully on be06c9d

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/44982.}

[viocassel]

I have tested this item ✅ successfully on be06c9d

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/44982.}

[QuyTon]

RTC

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/44982.}

[HLeithner]

thx