in AutoSuggestAPITest make sure static var overrides are undone after the test finishes

[diosmosis]

Description:

Currently this is done outside the test class, in the global scope, which means it will be run if the file is included and not undone. This is a problem if you write your own tests for the autosuggest API in a plugin, and expect the value to be it's default (because phpunit will include the file when running the plugin test suite).

This cost me about ~6 hrs of debugging time to find so I thought I'd prevent it from happening again.

Review

• Functional review done
• Potential edge cases thought about (behavior of the code with strange input, with strange internal state or possible interactions with other Matomo subsystems)
• Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
• Security review done
• Wording review done
• Code review done
• Tests were added if useful/possible
• Reviewed for breaking changes
• Developer changelog updated if needed
• Documentation added if needed
• Existing documentation updated if needed