[12.x] Enhance the test coverage for Pipeline::through()

[azim-kordpour]

Hi,
This PR enhances the test coverage for the Pipeline::through() method to ensure that it overwrites previously set or appended pipes.

$object = new stdClass(); $object->value = 1; $pipeline ->through([MultiplyByTwo::class]) // Would make it 2 ->pipe([AddFive::class]) // Would make it 7 ->through([AddFour::class]) // Should reset and make it 5 ->thenReturn();