add agent setup support for 'rhel' distro name

[nagworld9]

Description

Rhel9+ distros changed the distro name to 'rhel' from 'redhat'

Issue #

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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 #2620 (5704dad) into develop (99d07d2) will decrease coverage by 0.00%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #2620      +/-   ##
===========================================
- Coverage    71.97%   71.96%   -0.01%     
===========================================
  Files          103      103              
  Lines        15606    15606              
  Branches      2483     2483              
===========================================
- Hits         11232    11231       -1     
  Misses        3864     3864              
- Partials       510      511       +1     

Impacted Files	Coverage Δ
azurelinuxagent/common/utils/fileutil.py	78.94% <0.00%> (-0.76%)	⬇️

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