Config - CompactThroughputBurst - Setting lower than default CompactThroughput is not accepted

Hi,

We are required to lower the IO of influx during compactions, however this does not seem possible in `v2.0.4` due to the following:

Only `CompactThroughputBurst` is exposed via config, not `CompactThroughput`. The configured `CompactThroughputBurst` is overriden during start-up to the default `48mb` of `CompactThroughput`. Thus setting `CompactThroughputBurst` lower than `48mb` has no effect.

https://github.com/influxdata/influxdb/blob/540bb66e1381a48a6d1ede4fc3e49c75a7d9f4af/tsdb/store.go#L264-L278

How would we go about it, exposing `CompactThroughput` or allowing lower than `48mb` for `CompactThroughputBurst`, though I'm unsure of just setting `Burst` is enough to lower the IO?

Thank you,
Marco Muller

Start by reading tsdb/store.go around lines 264-278 to trace how CompactThroughputBurst is initialized and overridden during startup. Determine the intended configuration behavior and verify that a lower configured throughput is honored without breaking compaction settings; no test file is named in the issue.

Written by the indexing model from the issue text.