Fix row header width jumping after adding/deleting rows to the dataset

[budnix]

Context

The PR fixes an issue where the row header jumps (the width was changed) after performing actions such as inserting or removing rows.

How has this been tested?

I tested the changes locally, and I covered the fix with a new E2E test.

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Related issue(s):

1. fixes https://github.com/handsontable/dev-handsontable/issues/471

Affected project(s):

• handsontable

Checklist:

• I have reviewed the guidelines about Contributing to Handsontable and I confirm that my code follows the code style of this project.
• I have signed the Contributor License Agreement

[github-actions]

Launch the local version of documentation by running:

npm run docs:review ff85a03e991a24b275b54bd9d16496ce286d6323