cgroups: accurate procfs parsing

[rockdrilla]

Description: split line into exactly 3 parts while parsing /proc/{pid}/cgroup.

Link to tracking Issue: #6389

Testing: None

Documentation: None

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: rockdrilla / name: Konstantin Demin (d29c947)

[bogdandrutu]

/cc @dashpole

[dashpole]

Can you add a test using the output from the bug report?

[rockdrilla]

@dashpole done.

[dmitryax]

@rockdrilla thanks for the contribution! Can you please add a changelog entry?

[codecov]

Codecov Report

Base: 91.86% // Head: 91.86% // No change to project coverage 👍

Coverage data is based on head (cc61f0d) compared to base (62f4388).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6462   +/-   ##
=======================================
  Coverage   91.86%   91.86%           
=======================================
  Files         237      237           
  Lines       13620    13620           
=======================================
  Hits        12512    12512           
  Misses        879      879           
  Partials      229      229           

Impacted Files	Coverage Δ
internal/cgroups/subsys.go	92.30% <100.00%> (ø)

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.

[rockdrilla]

@dmitryax I'm afraid I can't express that change in "human" words better than any of existing contributors. :)

[rockdrilla]

Got it, wait a minute.

[dmitryax]

Just create a file in https://github.com/open-telemetry/opentelemetry-collector/tree/main/.chloggen with a few words like Fixed Cgroup v1 initialization for memory_ballast extension with a link to the issue.