chore: [receiver/hostmetrics] Fix integration tests

[rogercoll]

Description

1. Integration tests that use /proc should not compare the PID, parent PID and owner attributes as they depend on the environment:

                        pmetrictest.IgnoreResourceAttributeValue("process.owner"),
			pmetrictest.IgnoreResourceAttributeValue("process.parent_pid"),
			pmetrictest.IgnoreResourceAttributeValue("process.pid"),

2. and 3. Root path was not correctly set, as the Config.Unmarshal() method is not called during this initialization. Fixed by using scraper's config interface:

                                pCfg.SetRootPath(rootPath)
				pCfg.SetEnvMap(setGoPsutilEnvVars(rootPath, &osEnv{}))

2. Some testdata/e2e/proc/1 required files were missing (statm, exe, cgroup, status).

Link to tracking issue

Fixes #32536

Testing

Documentation

[rogercoll]

Skip changelog?

[braydonk]

Triage: Adding skip-changelog since this is purely a test fix.

[braydonk]

Thanks for fixing this!

[braydonk]

If we're ignoring these attributes now anyway maybe these can be removed? Or does the integration test framework expect them in some way?

[rogercoll]

Good point, the test framework actually removes them, so let's remove them as well 3b5936a