Fix PHPStan for previous major

Problem/Motivation

🐛 Recent commits to *.3.x branches break BC Active fixed some compatibility issues for 10.x under the 3.3.x branch. However, there are some outstanding PHPStan warnings that weren't blockers, but should be fixed.

Steps to reproduce

See pipeline for

phpstan (previous major)</code).

<h3 id="summary-proposed-resolution">Proposed resolution</h3>

Some of the issues can be fixed with a before_script, to remove the attributes before phpstan (previous major) runs:
<code>
phpstan (previous major):
  before_script:
    - if [[ "$DRUPAL_CORE" =~ ^10 ]]; then
    -   sed -i '/#\[Legacy.*\]/d' $DRUPAL_PROJECT_FOLDER/*.module $DRUPAL_PROJECT_FOLDER/*.inc $DRUPAL_PROJECT_FOLDER/modules/*/*.module $DRUPAL_PROJECT_FOLDER/tests/modules/*/*.module
    -   sed -i '/^.*#\[\(Hook\)\(.*\)\].*$/d' $DRUPAL_PROJECT_FOLDER/src/Hook/*.php $DRUPAL_PROJECT_FOLDER/modules/*/src/Hook/*.php $DRUPAL_PROJECT_FOLDER/tests/modules/*/src/Hook/*.php
    - fi

There are some other problems that will need further investigation.

Remaining tasks

2. Investigate other warnings.

User interface changes

None.

API changes

None.

Data model changes

None.