Metrics time cost not equal with Span duration

[danielqsj]

Describe the bug
In io.opentelemetry.instrumentation.api.instrumenter.Instrumenter,
There will calculate the startTime and endTime for both span and metrics.
But due to the interface of timeExtractor is only implemented by a few of instrumentation,
so the startTime and endTime in span and metrics are different.

In most cases, the time cost (metrics endTime - metrics startTime) in metrics will be smaller than the correspond span duration (span endTime - span startTime).

This is confusing for end users.

Steps to reproduce
Invoke most cases of call.

What did you expect to see?
The time cost (metrics endTime - metrics startTime) in metrics is equal with the correspond span duration (span endTime - span startTime).

What did you see instead?
In most cases, the time cost (metrics endTime - metrics startTime) in metrics will be smaller than the correspond span duration (span endTime - span startTime).

What version are you using?
v1.11.1

[mateuszrzeszutek]

Also related: #4690

[danielqsj]

@mateuszrzeszutek is there any plan to enhance it ?