chore: use utc time in logs to avoid user location getting disclosed

[chaitanyaprem]

Description

fixes #1191

Changes

• changed default source to return time in UTC . @richard-ramos i have noticed NTP is not being used in status, but if NTP is used would the timesource provide time in UTC or local tz?
• changed other places where time is logged to use UTC

[richard-ramos]

if NTP is used would the timesource provide time in UTC or local tz?

You would get the local time

[richard-ramos]

Is this change because of logging? because if so I wonder if we should instead create a logging utils that receives a time and automatically converts it into UTC, instead of modifying the code to use UTC? Something like this in logging/logging.go:

func UTCLogger(key string, t time.Time) zap.Field {
	return zap.Time(key, time.UTC())
}

Then we'd look for all the instances of zap.Time in the code and replace it by logging.UTCTime (which seems to happen only in 4 places)