Data Retention Value not being set with VM

When users on an older version of PMM or even on a fresh install(dev-latest), provide a custom Data retention period, we are not passing the same to VM. 

Steps to recreate:

1) Install PMM 2.11.1, set Data_Retention  to 1 day or 2 days or x days. 
2) Check PMM-Setting if the Data Retention value is being shown correctly. 
3) Enable testing Repo and Upgrade to Latest PMM Dev version, after Upgrade
4) Download PMM-Server logs, check the victoriametrics.ini file, see the value being passed to dataRetention. 

5) Get in pmm-server docker container, check the output for `ps aux | grep victoria` see the actual parameter passed, it is not the same as provided by user. 

This issue is with both Upgraded instances as well as new Instances. 

Providing data retention in Days to VM is supported by VM v1.45+ and it can be found on the release notes https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/CHANGELOG.md#v1450  and https://github.com/VictoriaMetrics/VictoriaMetrics#retention 

Expected Behaviour: 

Users Data Retention Period or Default must be used, and should not change for upgraded as well new instances.