Deprecate icons sizes iteratively

As was figured out in this discussion we cannot deprecate 10 && 18 icons sizes at once as they are widely used in the GitLab codebase. The deprecation should be done iteratively.

The plan is outlined below:

• Revert !2027 (merged) - !2053 (merged)
• Create new MR including !2027 (merged) changes + updated validator that will validate based on whether use-deprecated-sizes was provided or not - suggested implementation - !2065 (merged)
• Integration MR for GitLab project that will add use-deprecated-sizes wherever needed - gitlab!55638 (merged)
• Epic to remove all occurrences of use-deprecated-sizes - &5623 (closed)
• MR to get rid of the validator and deprecated sizes after the epic is closed