Fix units of process.open_file_descriptor.count and process.context_switches

[ChrsMark]

Fixes #1662

Changes

This PR fixes the units of process.open_file_descriptor.count and process.context_switches metrics.
I was not sure if it should be {open_file_descriptor} or just {file_descriptor} but went with what was proposed in #1662.

Merge requirement checklist

• CONTRIBUTING.md guidelines followed.
• Change log entry added, according to the guidelines in When to add a changelog entry.
  • If your PR does not need a change log, start the PR title with [chore]
• schema-next.yaml updated with changes to existing conventions.

[braydonk]

I believe {open_file_descriptor} is correct as a unit to match the name. This does make me wonder if the word open even needs to be in the name though; file_descriptor itself implies that it's open. Let's merge this though, and I'll make a separate issue for that now.

[lmolkova]

maybe {descriptor} or {file_descriptor}?

I assume that if we had some other counter for file descriptors, it'd be right to use the same unit

[arminru]

^ +1

[ChrsMark]

Answerwing with my original concern from the PR description :) :

I was not sure if it should be {open_file_descriptor} or just {file_descriptor} but went with what was proposed in #1662.

It makes sense to change it to file_descriptor all together as @braydonk suggests at #1797 (comment).

I'm fine if we want to merge this one and iterate on it, or if we want to fix in a different PR entirely.

[braydonk]

Let's merge this PR with the suggested change to {file_descriptor}, I opened #1798 and if folks all agree we can make the metric name change as part of that.

[arminru]

^ +1