[PostRector] Keep imports used in an earlier docblock of a node with stacked docblocks

[Adelagric]

With ->withImportNames(removeUnusedImports: true), a node carrying two docblocks loses the imports referenced only in the first one:

use App\Attr\First;
use App\Attr\Second;

final class Foo
{
    /**
     * @First
     */
    /**
     * @Second
     */
    public $bar;
}

use App\Attr\First; is removed, with no rule applied. The same two annotations in a single docblock are fine; with three stacked docblocks, the first two imports go.

Cause: UnusedImportRemovingPostRector::findNamesInDocBlocks() checks each docblock on a clone $node with setDocComment($doc), but the clone keeps the PHP_DOC_INFO attribute already resolved for the original node — i.e. its last docblock — so createFromNodeOrEmpty() returns that cached PhpDocInfo instead of parsing $doc. Only the last docblock is ever scanned. It shows as soon as anything resolved the node's docblock earlier in the run: DocblockNameImportingPostRector with importDocBlockNames (the default), or any rule reading the docblock — which is why the existing fixtures, whose configs do neither, pass.

Fix: clear the attribute on the clone. Fixture added to tests/Issues/NamespacedUseAutoImport (its config already enables both removeUnusedImports() and importNames()); it fails on main (-use Carbon\CarbonInterface;) and passes with the change. Full suite: 5290 tests green; ecs and phpstan report nothing new on the changed file.

[TomasVotruba]

This would break a docblock standard that is generally recognized and would lead to unexpected consequences.

Fix the docblock to one instead.