Twenty Twenty-One: Update IE specific editor stylesheet

[desrosj]

The IE specific editor stylesheet was not regenerated correctly when [50493] was committed.

Running npm run build results in new changes that should be committed.

[desrosj]

In 50667:

Twenty Twenty-One: Rebuild IE specific editor stylesheet.

This was not updated to include the changes from [50493].

Fixes #52981. See #52702.

[desrosj]

Reopening to consider for releasing with 5.7.1.

Related #52859.

[peterwilsoncc]

In 50680:

Twenty Twenty-One: Rebuild IE specific editor stylesheet.

This was not updated to include the changes from [50493].

Props desrosj.
Merges [50667] to the 5.7 branch.
Fixes #52981. See #52702.