[hostcfgd] Wait for chage before checking status

[dlanov]

Why I did it

PasswHardening.passwd_aging_expire_modify() checked the chage process status immediately with poll().

When the process was still running, poll() returned None. Because None != 0, hostcfgd logged a failure even when chage completed successfully.

Fixes #397.

Work item tracking

• Microsoft ADO: N/A

How I did it

• Replaced the immediate poll() call with wait() so hostcfgd checks the completed process exit status.
• Preserved the existing chage command arguments and nonzero-return error message.
• Added focused unit tests for successful and failed chage execution.
• Mocked the subprocess and syslog calls so the tests do not modify real user accounts.

How to verify it

Completed locally:

• git diff --check
• python3 -m py_compile scripts/hostcfgd tests/hostcfgd/hostcfgd_passwh_test.py

The compile check completed successfully with two pre-existing SyntaxWarning messages for unrelated escape sequences in scripts/hostcfgd.

The focused tests could not be executed locally because the environment does not have pytest or the parameterized test dependency installed.

In a SONiC host-services test environment, run:

python3 -m pytest \
  tests/hostcfgd/hostcfgd_passwh_test.py \
  -k 'passwd_aging_expire_modify' \
  -v

To run the full password-hardening test file:

python3 -m pytest \
  tests/hostcfgd/hostcfgd_passwh_test.py \
  -v

Previous behavior

A successful chage process could still generate:

failed: return code - None

New behavior

Hostcfgd waits for chage to complete and logs the existing error only when the process exits with a nonzero status.

[mssonicbld]

/azp run

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[mssonicbld]

Hi, there are workflow run(s) waiting for approval, you may be first-time contributor. I will notify maintainers to help approve once PR is approved. Thanks!

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