[2.3.0] Checkmk Werk 16897 created: chrony: wrong handling of 'n/a' values for 'Ref time (UTC)' and 'Stratum'

[//]: # (werk v2) # chrony: wrong handling of 'n/a' values for 'Ref time (UTC)' and 'Stratum' key | value ---------- | --- date | 2024-09-25T11:16:41+00:00 version | 2.3.0p19 class | fix edition | cre component | checks level | 1 compatible | yes A chrony status without a valid server also contains invalid values for 'Stratum' and 'Ref time', resulting in a 'Time since last sync' of 54 years 256 days being reported (which is the difference to epoc := 1.1.1970). This change just skips reporting 'Stratum' and 'Time since last sync' if we don't have a valid server (address).