Fix strong reference in Cleaners

[Bobcat66]

Description

Removed the strong reference in the Object Detector cleaners, which prevented the object from ever being cleaned up

Closes #2044

Meta

Merge checklist:

• Pull Request title is short, imperative summary of proposed changes
• The description documents the what and why, including events that led to this PR
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[Gold856]

Your solution is a bit overkill. Cleaner offers guarantees that make most of the logic that was previously necessary unneeded. Look into the docs for Cleaner, and also how it's implemented here: https://github.com/wpilibsuite/allwpilib/blob/7ca35e5678cf32caec6a1a866ca51d0136c4c398/wpinet/src/main/java/edu/wpi/first/net/MulticastServiceAnnouncer.java

[Gold856]

Awesome, thanks!