fix: Get the pid of xcom command dynamically

[Laerte]

fix: #45047

When share process namespace is set, the pid will never be 1, thus failing to execute kill command of xcom sidecar container, so we need to get the pid dynamically using pgrep.

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[boring-cyborg]

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[jscheffl]

Thanks - this looks like a good idea!

[boring-cyborg]

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