[Forwardport] Fix for parsing attribute options labels, when & used.

[mage2pratik]

Original Pull Request

#18354

Description

After updating Magento to 2.2.6 when attribute is saved, and option label contains & label is cut before &. It is caused by usage of function parse_str() which is confused by &

Fixed Issues (if relevant)

Manual testing scenarios

1. Add attribute option with label containing char &
2. Save attribute
3. Check if label wa correctly saved.

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)

[josefbehr]

@mage2pratik Thanks for the contribution. Please fix the failing tests and consider renaming the variable to something a bit shorter (or just replace the $serializedValue).

[josefbehr]

@mage2pratik Sorry, but I have to close this PR, as there already exists an internal ticket to fix the issue (see #18293 (comment))

edit: Actually, let me check to be sure

[josefbehr]

Just confirmed that this is already fixed in 2.3