Fingerprinting 2.0: User Agent - follow up to #12638

[pes10k]

We have some reports of the Android device info reappearing in the Android UA, w/ or w/o farbling.

This issue is to i) correct the regression if it can be reproduced, and ii) add / correct the tests so we can catch any future possible regressions faster in the future

(see "pixel 4a (5G)" in the UA below

[srirambv]

+1 from @ristein and @svilupposoftware via #15103

[srirambv]

+1 from @Brave-Matt via #15322.

@pes10k @pilgrim-brave issue is missing milestone. Since its already landed on nightly need to decide which milestone this will go in.

cc: @rebron @bbondy