[LakshmikanthRaju]

What does this PR do?

Do not fail service.dead/service.disabled for services that are not present

A service that is not present is by definition neither running nor enabled, so these states should pass.

• service.dead now passes in test mode too, matching service.disabled
• treat a unit lookup error ("Failed to get information on unit") as "not present" in service.dead and service.disabled; offline mode and daemon-reload errors still fail
• systemd_service._check_available returns False on exit status 4 when the systemd version is unknown and the output cannot be parsed

What issues does this PR fix or reference?

Fixes #70396

Previous Behavior

When specifying state service.dead/service.disabled with a service that is not present on the system, the state will fail.

New Behavior

Do not fail service.dead/service.disabled for services that are not present

Testing

Upgrade salt and ran the below commands to test the fix

[worker@lvn-dvm-10-161-243-165 salt-service-missing-fix]$ sudo salt-call --local state.single service.disabled nosuchsvc
local:
----------
          ID: nosuchsvc
    Function: service.disabled
      Result: True
     Comment: The named service nosuchsvc is not available
     Started: 06:57:33.300536
    Duration: 44.874 ms
     Changes:   

Summary for local
------------
Succeeded: 1
Failed:    0
------------
Total states run:     1
Total run time:  44.874 ms
[worker@lvn-dvm-10-161-243-165 salt-service-missing-fix]$ sudo salt-call --local state.single service.dead nosuchsvc
local:
----------
          ID: nosuchsvc
    Function: service.dead
      Result: True
     Comment: The named service nosuchsvc is not available
     Started: 06:57:51.810232
    Duration: 36.923 ms
     Changes:   

Summary for local
------------
Succeeded: 1
Failed:    0
------------
Total states run:     1
Total run time:  36.923 ms
[worker@lvn-dvm-10-161-243-165 salt-service-missing-fix]$ sudo salt-call --local state.single service.dead nosuchsvc test=True
local:
----------
          ID: nosuchsvc
    Function: service.dead
      Result: True
     Comment: The named service nosuchsvc is not available
     Started: 06:58:25.991916
    Duration: 39.134 ms
     Changes:   

Summary for local
------------
Succeeded: 1
Failed:    0
------------
Total states run:     1
Total run time:  39.134 ms
[worker@lvn-dvm-10-161-243-165 salt-service-missing-fix]$ sudo salt-call --local state.single service.enabled nosuchsvc
[ERROR   ] The named service nosuchsvc is not available
local:
----------
          ID: nosuchsvc
    Function: service.enabled
      Result: False
     Comment: The named service nosuchsvc is not available
     Started: 06:58:40.325711
    Duration: 38.457 ms
     Changes:   

Summary for local
------------
Succeeded: 0
Failed:    1
------------
Total states run:     1
Total run time:  38.457 ms

Merge requirements satisfied?

[NOTICE] Bug fixes or features added to Salt require tests.

• Docs
• Changelog - https://docs.saltproject.io/en/master/topics/development/changelog.html
• Tests written/updated

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