Add support for python 2.6 to the log collection code

[kevinclark19a]

Description

Relaxes the requirements for the log collection background task to allow for python2.6 to run it. Right now, there aren't any distros that are on python2.6 and also have cgroups enabled (another requirement of that code running), but if/when cgroups are enabled for those distros, the log collection background task will also be enabled for those distros.

Also makes the log collection code python2.6 compatible, which right now allows waagent -collect-logs to be ran on distros with python2.6.

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PR information

• The title of the PR is clear and informative.
• There are a small number of commits, each of which has an informative message. This means that previously merged commits do not appear in the history of the PR. For information on cleaning up the commits in your pull request, see this page.
• If applicable, the PR references the bug/issue that it fixes in the description.
• New Unit tests were added for the changes made

Quality of Code and Contribution Guidelines

• I have read the contribution guidelines.

[codecov]

Codecov Report

Merging #2452 (0908556) into develop (28b429e) will increase coverage by 0.00%.
The diff coverage is 83.33%.

@@           Coverage Diff            @@
##           develop    #2452   +/-   ##
========================================
  Coverage    71.88%   71.88%           
========================================
  Files          101      101           
  Lines        14964    14968    +4     
  Branches      2369     2370    +1     
========================================
+ Hits         10757    10760    +3     
  Misses        3728     3728           
- Partials       479      480    +1     

Impacted Files	Coverage Δ
azurelinuxagent/common/logcollector.py	88.54% <80.00%> (-0.25%)	⬇️
azurelinuxagent/ga/collect_logs.py	82.26% <100.00%> (ø)

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[narrieta]

if zipfile.Zipfile raises then the finally clause will raise a null (None) reference exception