Missing changing class name from .custom-file-control to custom-file-label

Created by: ysds

The old .custom-file-control class have been rewrited to .custom-file-label in #25068.

Related diff: https://github.com/twbs/bootstrap/pull/25068/files#diff-e5540857a54676b43146ad92add2dbde

But .custom-file-control class is still exist in the current SCSS: https://github.com/twbs/bootstrap/blob/470b4472c63f444851c2bc5b7e6cf838103a621a/scss/_custom-forms.scss#L250-L257