Ease upgrade of duration properties inside configuration service

We introduce new APIs in ConfigurationService within NXP-26181 which allow us to get Integer, Long and Duration.

The last one can be problematic when we introduce properties which needs to be backported because the format change from a string/number representation to duration presentation (JDK one or a custom Nuxeo one, see NXP-25402).
For instance we defined in Nuxeo <= 9.10:

my.property=4

While we can define in Nuxeo >= 10.10:

my.property=4s
# or
my.property=4m

This change of format prevent us to use new Duration API in many cases. When unit is missing in the property value, we might log the usage to encourage users to upgrade to a unit with a value and we should fallback on unit seconds. As it we can define:

my.property=4 # for Nuxeo <= 9.10
my.property=4s # for Nuxeo >= 10.10