Deprecate third party code from host metrics receiver

[james-bebbington]

The Host Metrics receiver currently includes third party code for retrieving windows performance counter info, which is used to calculate load and paging metrics. We also calculate page file usage from a direct syscall into psapi.dll.

Ideally, we would like to upstream code to gopsutil to calculate these values directly so we can remove this code from the Collector repo.

[james-bebbington]

Updated plans for this:

1. The Host Metrics receiver currently uses third party code that accesses pdh.dll to extract perf counter data. This is useful for getting generic performance counter data, so will move this code to Contrib and create a perf counter receiver that targets Windows only. That receiver will be useful for generating stats on IIS, SQL Server, etc. Tracked in Add Windows Performance Counters Receiver opentelemetry-collector-contrib#1088.
2. Update core to use https://github.com/leoluk/perflib_exporter (note this is also used by https://github.com/prometheus-community/windows_exporter). This package reads from the Windows registry directly so
3. Upstream page file usage calls to gopsutil (this is still the long term plan)

Benefits of (2):

• Slightly faster since reading from the registry directly
• Can remove third_party code from Core 🎉
• Don't need to refactor the current third_party code to be accessible from Contrib. Just move it to Contrib instead as part of (1).
• Don't need to reverse engineer Sums from rates, and can report the Sums since boot time instead of since process start.

[tigrannajaryan]

@james-bebbington are we done with this issue?

[james-bebbington]

There is one comment above about moving the pagefile syscalls to gopsutil which is not done but that is not third party code and not very high priority so yes I think it makes sense to close this issue: all third party code is gone 👍