Metrics refactoring

[ateska]

Currently, metrics produced by the SeaCat Auth are a bit illogical and should be refactored:

• help attribute should be removed (at least from the propagation to InfluxDB)
• unit attribute should be removed (at least from the propagation to InfluxDB)

^- these two may be about the implementation in the InfluxDB forwarded in ASAB, it is linked with Prometheus implementation.

• sessions and anonymous_sessions metrics should be unified into: sessions: regular / anonymous.

seacat-auth/seacatauth/session/algorithmic.py

Line 44 in 27011e0

self.AnonymousSessionCounter: asab.metrics.Counter = self.MetricsService.create_counter(

seacat-auth/seacatauth/session/service.py

Line 84 in 27011e0

self.SessionGauge = self.MetricsService.create_gauge(

Proposed change:

self.AnonymousSessionCounter: asab.metrics.Counter = self.MetricsService.create_counter(
			"sessions",
			tags={"help": "Number of anonymous sessions created."},
			init_values={"anonymous": 0}
)

self.SessionGauge = self.MetricsService.create_gauge(
			"sessions",
			tags={"help": "Counts active sessions."},
			init_values={"regular": 0}
)