[8.x] Fix formatWheres in DatabaseRule

[lloricode]

When we try this, all validation will failed

// controller level

$this->validate($request, [
    'some_field' => Rule::exists(ModelClass::class)->where('extra->field', true),
]);

Checking return of DatabaseRule formatWheres will return

"extra->field,"1""

Now the PR fixes return is

"extra->field,true"

Thank you

[taylorotwell]

Had to revert this. Breaking people's applications.

[driesvints]

@lloricode fyi: #36459

[lloricode]

@lloricode fyi: #36459

Thank you for informing us

[niefufeng]

Should be consistent with builder query