update current memory usage check on log collector cgroup

[nagworld9]

Description

Systemd cgroup slice somehow gets left behind not cleaned up after logcollector finished. Due to this, max_memory_usage counter not cleaned up for next log collector run. When we check for memory limit, we may get old value and disable the log collector based on that which is not right. So, I updated that logic and consider only memory.stat(RSS+cache+SWAP) to check current memory_usage.

Issue #

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PR information

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• New Unit tests were added for the changes made

Quality of Code and Contribution Guidelines

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[codecov]

Codecov Report

Merging #2658 (100a58a) into develop (3aebcdd) will decrease coverage by 0.00%.
The diff coverage is 0.00%.

@@             Coverage Diff             @@
##           develop    #2658      +/-   ##
===========================================
- Coverage    71.97%   71.97%   -0.01%     
===========================================
  Files          103      103              
  Lines        15692    15688       -4     
  Branches      2486     2485       -1     
===========================================
- Hits         11295    11291       -4     
  Misses        3881     3881              
  Partials       516      516              

Impacted Files	Coverage Δ
azurelinuxagent/ga/collect_logs.py	81.15% <0.00%> (-0.36%)	⬇️

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