Remove calls to PHP 8.5-deprecated setAccessible

[jnoordsij]

WHY

These are no-op as of PHP 8.1 and thus no longer needed:

See also https://wiki.php.net/rfc/make-reflection-setaccessible-no-op

BEFORE - What was wrong? What was happening before this PR?

There were no-op calls triggering deprecations on PHP 8.5

AFTER - What is happening after this PR?

Obsolete code is gone and no more deprecations.

HOW

How did you achieve that, in technical terms?

Is it a breaking change?

No

How can we test the before & after?

If the PR has changes in multiple repos please provide the command to checkout all branches, eg.:

git checkout "dev-branch-name" &&
cd vendor/backpack/crud && git checkout crud-branch-name &&
cd ../pro && git checkout pro-branch-name &&
cd ../../..