Add mechanism to remove deprecated WorkManager jobs

[malmstein]

Task/Issue URL: https://app.asana.com/0/414730916066338/1173445999500153/f

Description:

• We use WorkManager to enqueue work that will be done in the background at some point in the future.
• Some experiments will use this feature to schedule future work. Android: Sticky Search Notification is an example.
• When the experiment is removed, we need to make sure that those scheduled jobs are also removed from the user's device.

Our current implementation has AndroidNotificationScheduler cleaning up old jobs AND scheduling new work. The idea in this PR is to separate the responsibilities making it more readable.

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Internal references:

Software Engineering Expectations
Technical Design Template

[CDRussell]

Looks like there's now some duplicate code left over in NotificationScheduler

1. it still also tries to cancel unnecessary work
2. it also defines deprecated work tag list

[malmstein]

@CDRussell I've changed how the WorkManager is initialized for testing according to the documentation. This has shown that we were not properly testing it, for that I've created a TestWorker that has no dependencies and it's sole purpose is to be tested

[malmstein]

we set this delay because if we don't the Worker will be immediately completed.

[CDRussell]

This is great, and i never knew about that worker testing lib so excited to see its inclusion.

Some minor tidy-up suggestions. Feel free to merge after (no re-reviewing needed)

1. Remove sticky search comment from JobCleaner
2. Format JobCleaner class
3. Format JobCleanerTest class

Great stuff! 👍

[CDRussell]

Looks like there's now some duplicate code left over in NotificationScheduler

1. it still also tries to cancel unnecessary work
2. it also defines deprecated work tag list

Heads up that this comment hasn't been addressed