[Rework] Do not lowercase all data send to ClickHouse

[Rework] Do not lowercase all data send to ClickHouse

A lot of strings stored in ClickHouse are case sensitive according to
standards - store them in original case. We can always can use
'lower(field)' in a ClickHouse query, but if string was lowercased by
Rspamd nothing can be done to recover lost information.

Lowercase domain parts of addresses - domains are not case sensitive and
storing them in lower case will simplify queries.