What does this implement/fix?

Change default value of ntp.sync.rtc.set to false. The motivation of this change was a recent discussion with @Bucking-Horn that brought to light that there are systems where the RTC is expected to be set to local time (instead of UTC) for coexistence with other operating systems (such as Windows).

This is not really a problem here as we also have ntp.sync.rtc.utc to control whether the RTC should be set to, well, UTC (true) or local time (false), however, there exists no standardized way to obtain if the RTC is meant to be set in local time or not. The RTC itself doesn't know this and, hence, cannot be queried. To avoid such conflicts, we decide to not set the RTC by default but only if users specifically want it. If they do, they can also set the UTC/localtime option.

Related issue or feature (if applicable): N/A

Pull request in docs with documentation (if applicable): N/A

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