amp-social-share causes layout shift on upgrade

## What's the issue?

When `.i-amphtml-unresolved` class is removed on component upgrade, overflow is changed from `hidden` to `visible`, which causes subsequent elements to shift (both sibling inline element and following image).

This issue was surfaced by this issue from the Page Experience tool (https://github.com/ampproject/wg-performance/issues/48).

This may be related to https://github.com/ampproject/amphtml/issues/27228 but `data-mode=replace` is not used in the example.

## How do we reproduce the issue?

Visit the URL below with "Layout Shift Regions" enabled in Rendering tab of Chrome Dev Tools to visualize the layout shift.

https://tasty.co/amp/recipe/garlic-bread-bruschetta

## What browsers are affected?

Chrome 87

## Which AMP version is affected?

2009252320001

Reproduce the layout shift at the tasty.co AMP URL with Chrome DevTools' Layout Shift Regions enabled, then inspect the amp-social-share upgrade path where `.i-amphtml-unresolved` is removed. Done means upgrading the component no longer shifts the sibling inline element or following image when overflow changes.

Written by the indexing model from the issue text.