Fix switching back to previous locale after switching based on hintLocales

[eranl]

Turns out there are multiple instances of the same InputMethodSubtype, which caused this condition to incorrectly hold true.

Possibly related to #596 (comment).

[Helium314]

Thanks for finding this, how did you notice?

Can you tell where the multiple instances are coming from? Might be better to fix it there, because a unwanted failing equals check could also cause problems in other places.
My first guess would be it's related to custom subtypes that get created from SettingsSubtype.

[eranl]

how did you notice?

While testing emoji search hintLocales.

Can you tell where the multiple instances are coming from?

Looks like they come from the async parcel-ization.

[eranl]

While testing #1816, I found another failure mode. See fe52309.