Update location with updateChildValues

[RaMin0]

Use updateChildValues (and setPriority) in favor of setValuesAndPriority to avoid overwriting other child values.

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[RaMin0]

I signed it!

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CLAs look good, thanks!

[morganchen12]

@mcdonamp please review

[asciimike]

@RaMin0 @morganchen12 it looks like we don't actually need priority (we store the geohash in g and query by that, rather than priority), so I'd just remove the code and tests for priority and use update, no need to do the second update.

Presumably this is so you can store additional data alongside the GeoFire info?

[RaMin0]

@mcdonamp: Presumably this is so you can store additional data alongside the GeoFire info

Yes, it made more sense to save the related info stored in the same node rather than having a parallel node that I have to maintain just to keep the extra info.

One other thing I suggest to do is to make the name of the location key (currently l) configurable, to give more context. pickUpLocation is more significant than just l. But that's an issue for another PR.

[RaMin0]

@mcdonamp Check 96f40431d0d0fe3aac66bc0302da6c9cf3ab2f58.