[6.x] Don't return nested data from validator when failing an exclude rule

[hackel]

When using the exclude_if or exclude_unless validation rules, nested fields are excluded from being validated, however they are not being removed from the validated data.

This is a breaking change, however I would consider it a bugfix since the documentation is clear that "The field under validation will be excluded from the request data returned by the validate and validated methods."

The existing test case for this feature did not reflect the intended behaviour, so I just corrected that test rather than including a new one.

[taylorotwell]

Please give an example.

[hackel]

The test case I modified in ValidationValidatorTest::testExcludeIf demonstrates the issue. It uses the following rules:

[
    'vehicles.*.type' => 'required|in:car,boat',
    'vehicles.*.wheels' => 'exclude_if:vehicles.*.type,boat|required|array',
    'vehicles.*.wheels.*.color' => 'required|in:red,blue',
    // In this bizzaro world example you can choose a custom shape for your wheels if they are red
    'vehicles.*.wheels.*.shape' => 'exclude_unless:vehicles.*.wheels.*.color,red|required|in:square,round',
]

With this data:

[
    'vehicles' => [
        [
            'type' => 'car',
            'wheels' => [
                ['color' => 'red', 'shape' => 'square'],
                ['color' => 'blue', 'shape' => 'hexagon'],
                ['color' => 'red', 'shape' => 'round', 'junk' => 'no rule, still present'],
                ['color' => 'blue', 'shape' => 'triangle'],
            ],
        ],
        ['type' => 'boat'],
    ],
]

This produces identical validated data, however we expect the exclude_if rule to remove the vehicles.*.wheels.*.shape values from the validated output when color != red (hexagon and triangle), but currently they remain because only the first level of of validated data is removed by the unset statements. Changing these to Arr::forget fixes this to also remove the nested data.