fix/3450: Events passed to onChange erroneously triggered shouldForce

[BoardJames]

Description

This is a fix for #3450 which caused too many undo events to be created.

How Has This Been Tested?

Manual testing on Firefox and Chrome shows that the undo buttons work again with this fix.

Types of changes

Bug fix.

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows has proper inline documentation.

[codecov]

Codecov Report

Merging #3487 into master will not change coverage.
The diff coverage is 0%.

@@           Coverage Diff           @@
##           master    #3487   +/-   ##
=======================================
  Coverage   34.64%   34.64%           
=======================================
  Files         260      260           
  Lines        6737     6737           
  Branches     1219     1219           
=======================================
  Hits         2334     2334           
  Misses       3717     3717           
  Partials      686      686

Impacted Files	Coverage Δ
blocks/editable/index.js	10.79% <0%> (ø)	⬆️

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