Use local timezone of the host server in this case. The timezone can be overridden
with TZ environment variable if needed.
While at it, allow using whitespace instead of T as a delimiter between data and time
in the ingested _time field. For example, '2024-09-20 10:20:30' is now accepted
during data ingestion. This is valid ISO8601 format, which is used by some log shippers,
so it should be supported. This format is also known as SQL datetime format.
Also assume local time zone when time without timezone information is passed to querying APIs.
Previously such a time was parsed in UTC timezone. Add `Z` to the end of the time string
if the old behaviour is preferred.
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6721
4d27933041