Trim property attribute value

[khdc]

Description:

Trim the property attribute value in FormatThicknessService to prevent an exception when processing IsMatch.

Fixes # 371

Checklist:

• [X] I have commented my code, particularly in hard-to-understand areas
• [X] My changes generate no new warnings
• [ ] I have added tests that prove my fix is effective or that my feature works
• [X] New and existing unit tests pass locally with my changes
• [ ] I have tested my changes by running the extension in VS2017
• [ ] I have tested my changes by running the extension in VS2019
• [X] I have tested my changes by running the extension in VS2022
• [ ] If changes to the documentation are needed, I have noted this in the description above