Add ability to observe the number of connections halibut opens for ea…

[pawelpabich]

…ch polling subscription

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[pawelpabich]

I've moved the connection limit enforcement closer to the code that it applies to.

1. There is no need to perform work for other types of remote identities
2. We were executing IdentifyAsServerAsync even for the default switch case, which results in an exception. This shows how easy it is to make a mistake if code that is case-specific is applied to all cases.