influx reporter: make reporting precision configurable.

[Asaf-m]

No description provided.

[Asaf-m]

Here's an example of difference that can result from using higher precision. Below are the Ad performance saver steps monitoring graphs:
Before:

After (with millisecond precision):

Note that even in the "after" the graphs jump from 3(fetching) to 5(saving) skipping 4(processing). That's because the processing is so fast that it falls under the same millisecond. Using micro/nano second precision won't help as Grafana is hardcoded configured to millisecond precision (source).

[Asaf-m]

Note that the old code was rounding the time (same for events time at line 127). I thought this is an unexpected behavior so I removed the rounding part. In other words, for "seconds" precision for example, the code drops the milliseconds data.