add seperate info metric per homeserver to reduce label growth

[n0emis]

I've added a seperate info metric which looks like the following:

synapse_usage_info{database_engine="psycopg2",database_server_version="14.14",homeserver="localhost",log_level="INFO",python_version="3.12.7",server_context="None"} 1.0

And removed everything except homeserver from all other metrics. This way the set of labels on all metrics will not grow with every update/change to the homeserver

[loelkes]

Oh, thank you! I'll have a look. Sorry for not answering sooner.