minor #29231 SCA: consolidate non empty array checks across codebase (kalessil)

This PR was squashed before being merged into the 3.4 branch (closes #29231).

Discussion
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SCA: consolidate non empty array checks across codebase

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

This PR replaces `is_array(...) && count(...) > 0` with `... && is_array(...)` construct used in the codebase.

Commits
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2f1fd54dda SCA: consolidate non empty array checks across codebase

Author: nicolas-grekas

Extension/Validator/Constraints/FormValidator.php

@@ -48,7 +48,7 @@ public function validate($form, Constraint $constraint)
 
             // Validate the data against its own constraints
             if ($form->isRoot() && (\is_object($data) || \is_array($data))) {
-                if (\is_array($groups) && \count($groups) > 0 || $groups instanceof GroupSequence && \count($groups->groups) > 0) {
+                if (($groups && \is_array($groups)) || ($groups instanceof GroupSequence && $groups->groups)) {
                     $validator->atPath('data')->validate($form->getData(), null, $groups);
                 }
             }