[Fix-5199][TaskPlugin] Fix task process kill status check

[zhuxiangyi]

Purpose of the pull request

Fix task kill status checking when kill -0 returns Operation not permitted for an unkillable sudo parent process or when tenant login shell emits stderr with exit code 0.

Brief change log

• Add exit code accessor to ExitCodeException.
• Distinguish alive, not-alive, and no-permission process states in ProcessUtils.
• Continue killing permitted child processes instead of reporting success when only the sudo parent check is denied.
• Add unit coverage for sudo parent denied plus killable child processes.

Verify this pull request

• ./mvnw -pl dolphinscheduler-common,dolphinscheduler-task-plugin/dolphinscheduler-task-api -DskipTests -Djacoco.skip=true spotless:check
• ./mvnw -pl dolphinscheduler-task-plugin/dolphinscheduler-task-api -am -Dspotless.check.skip=true -Djacoco.skip=true -Dsurefire.failIfNoSpecifiedTests=false -Dtest=ProcessUtilsTest test

[boring-cyborg]

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[SbloodyS]

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