Refactor tracking parameter removal

[joshliebe]

Task/Issue URL: https://app.asana.com/0/1200204095367872/1208009677259118/f

Description

As mentioned in https://github.com/duckduckgo/Android/pull/4871, this adds some unit tests and cleans up the code in this class to make it a bit more readable.

Steps to test this PR

• [x] Visit http://privacy-test-pages.site/
• [x] Go to "Privacy Protections Tests” > “Query parameters"
• [x] Tap on the links
• [x] Verify that the parameters are stripped as expected

[joshliebe]

• #4879 👈
• develop

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