[DeadCode] Skip constant compare from vendor/ on NarrowWideUnionReturnTypeRector

[samsonasik]

When constant vendor can be different value, eg allow monolog v2 and v3:

"monolog/monolog": "^2.0 || ^3.0"

The Logger::API value are different. So this check is on purpose:

    public function createLogRecord(int $level): array|LogRecord
    {
        return Logger::API === 2
            ? ['level' => $level]
            : new LogRecord();
    }

and should be skipped.

[samsonasik]

@TomasVotruba ready 👍