Replace firewall-setup unit file if changed

[larohra]

Description

• Replace firewall-setup unit file if changed
• Remove custom service if firewalld service enabled and custom service also enabled

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.

[narrieta]

LGTM; minor comments

[narrieta]

would this need a daemon-reload?

[larohra]

No, I verified manually, it didnt complain for it (I just verified it in the one distro where we know firewalld is there - RHEL 8+)

[codecov]

Codecov Report

Merging #2236 (5e5c1fe) into release-2.3.0.0 (b8a006f) will decrease coverage by 0.00%.
The diff coverage is 79.31%.

@@                 Coverage Diff                 @@
##           release-2.3.0.0    #2236      +/-   ##
===================================================
- Coverage            70.61%   70.60%   -0.01%     
===================================================
  Files                   96       96              
  Lines                13616    13642      +26     
  Branches              1928     1932       +4     
===================================================
+ Hits                  9615     9632      +17     
- Misses                3584     3589       +5     
- Partials               417      421       +4     

Impacted Files	Coverage Δ
azurelinuxagent/common/persist_firewall_rules.py	77.05% <79.31%> (+0.66%)	⬆️
azurelinuxagent/ga/collect_telemetry_events.py	89.72% <0.00%> (-1.37%)	⬇️

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