Duration config did not take the correct format

Nobody has claimed this yet.

Please include configurations and logs if available.
Given _log.user.ttl=PT24H_ config
Janusgraph failed to parse the value.
The current implementation for Duration config parsing logic can be found from
https://github.com/JanusGraph/janusgraph/blob/master/janusgraph-core/src/main/java/org/janusgraph/diskstorage/configuration/backend/CommonsConfiguration.java#L96
It only support format like log.user.ttl=120000 ms.

For confirmed bugs, please report:

- Version:
- Storage Backend:
- Mixed Index Backend:
- Link to discussed bug:
- Expected Behavior:
- Current Behavior:
- Steps to Reproduce:

### Stack Trace (if you have one)

```
paste stack trace here
```

Start in janusgraph-core/src/main/java/org/janusgraph/diskstorage/configuration/backend/CommonsConfiguration.java around line 96, where Duration configuration parsing is implemented. Reproduce the failure with log.user.ttl=PT24H and compare it with the supported 120000 ms format. Done means the intended duration format is parsed correctly without breaking the existing format.

Written by the indexing model from the issue text.