Hide timezone notice when local and server timezones are the same

[dbaty]

Description

This takes space and is not very useful.

Now the notice is only printed when the local timezone is different from the server timezone, for example:

Using local time zone Europe/Paris (server uses Etc/UTC)
Use `set time zone <TZ>` to override, or set `use_local_timezone = False` in the config

Fixes #1579.

Demo

When local and server timezones are different:

$ pgcli
Using local time zone Europe/Paris (server uses Etc/UTC)
Use `set time zone <TZ>` to override, or set `use_local_timezone = False` in the config
Server: PostgreSQL 17.5 (Debian 17.5-1.pgdg110+1)
[...]

When timezones are the same:

$ pgcli
Server: PostgreSQL 17.5 (Debian 17.5-1.pgdg110+1)
[...]

Checklist

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