Fix OS capabilities

[grcevski]

There were few bugs in the OS capability checking which are being fixed with this PR:

1. If SYS_ADMIN is present, it effectively means all capabilities.
2. If we have kernel older than 5.8, SYS_ADMIN is a must, the others weren't split off yet.
3. If we have NET_ADMIN we also have NET_RAW, so we can relax that check.

Given that I failed to run Beyla with SYS_ADMIN, I don't think we should enforce the capabilities, we should only warn. This is very hard to get right 100% and it shouldn't be a hard check.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 91.30435% with 2 lines in your changes missing coverage. Please review.

Project coverage is 81.97%. Comparing base (4494fae) to head (146b064).
Report is 7 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/beyla/os.go	91.30%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1131       +/-   ##
===========================================
+ Coverage   68.13%   81.97%   +13.84%     
===========================================
  Files         140      141        +1     
  Lines       11520    11598       +78     
===========================================
+ Hits         7849     9508     +1659     
+ Misses       3156     1563     -1593     
- Partials      515      527       +12     

Flag	Coverage Δ
integration-test	57.15% <13.04%> (?)
k8s-integration-test	59.03% <13.04%> (?)
oats-test	36.91% <13.04%> (-0.14%)	⬇️
unittests	52.44% <82.60%> (+0.07%)	⬆️

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[rafaelroquetto]

Neat, thanks for the fix!