Remove requirement for sorting tags alphabetically in JSON output

[jmartisk]

OpenMetrics format doesn't have such requirement either.
Implementations can still decide to do it if they want to.

This also requires changes to the TCK tests so that they will pass even if the output is not sorted.

[rmannibucau]

Hi @jmartisk , can this requirement stay? This makes everthing deterministic and easier to integrate overall and it does not cost much in java side so think it is worth keeping - very worse case, the spec shouldn't forbid impl to do that.

[jmartisk]

This was just some kind of an idea, I'm not really sure if we want to do this. And doing this would mean changing the TCK, as stated in the description, and that would not be a very easy thing to implement, and the already (IMO) ugly TCK code would get even worse.

[donbourne]

sorting tags also makes it easier for people to scan through a list of metrics and see which ones have the same tags... so there's some benefit to it.

I don't have a strong opinion either way on this one.