Fixes #11163 missing data key code-entity in CMS page edit form

[Tomasz-Silpion]

Description

This fixes Data key is missing: code-entity Magento 2.2 fatal error while opening admin content pages CMS editor.

Fixed Issues (if relevant)

1. Magento 2.2.0 Pages showing error: Data key is missing: code-entity #11163: Magento 2.2.0 Pages showing error: Data key is missing: code-entity

Manual testing scenarios

1. Go to Stores -> Settings -> Configuration -> Sales -> Google API -> Google Analytics
2. Set following values: Enable - yes, Account Number - (any), Enable Content Experiments - yes
3. Try to edit Content -> Elements -> Pages -> (any page edit)

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[magento-cicd2]

All committers have signed the CLA.