[CodingStyle] Remove ConsistentImplodeRector from coding style level, as already in PHP 8.0 set

[TomasVotruba]

ConsistentImplodeRector is registered in both CodingStyleLevel and the PHP 8.0 set. The rule is not a style preference - implode($glue, $array) argument order became the only supported one in PHP 8.0, as the swapped implode($array, $glue) signature was removed. So it belongs to the PHP 8.0 set only.

The rule stays where it already is, in config/set/php80.php:

$rectorConfig->rules([
    // ...
    ConsistentImplodeRector::class,
]);

The change it makes:

-$itemsAsStrings = implode($items, '|');
+$itemsAsStrings = implode('|', $items);

Only the duplicate registration in src/Config/Level/CodingStyleLevel.php is dropped.