test(text-editor): refine keyboard tests

[paulrobinson88]

Proposed behaviour

• Adds 3 Storybook interaction tests to check correct keyboard interaction in different compositions of the text-editor component
• Removes redundant keyboard interaction tests from the Playwright file

Current behaviour

• There are a number of Playwright tests which cover different keyboard interaction for the text-editor component which could be covered elsewhere in the testing suite.

Checklist

• Commits follow our style guide
• Related issues linked in commit messages if required
• Screenshots are included in the PR if useful
• All themes are supported if required
• Unit tests added or updated if required
• Playwright automation tests added or updated if required
• Storybook added or updated if required
• Translations added or updated (including creating or amending translation keys table in storybook) if required
• Typescript d.ts file added or updated if required
• Related docs have been updated if required

QA

• Tested in provided StackBlitz sandbox/Storybook
• Add new Playwright test coverage if required
• Carbon implementation matches Design System/designs
• UI Tests GitHub check reviewed if required

Additional context

Testing instructions

• Check the 3 interaction stories load and execute as expected.