[release-1.20] oci: always reap conmon zombies

[openshift-cherrypick-robot]

This is an automated cherry-pick of #5510

/assign haircommander

Fix a case where conmon children are sometimes leaked

[haircommander]

/lgtm
/approve

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: haircommander, openshift-cherrypick-robot

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[openshift-bot]

/retest-required

Please review the full test history for this PR and help us cut down flakes.

[openshift-bot]

/retest-required

Please review the full test history for this PR and help us cut down flakes.

[haircommander]

/lgtm

[openshift-bot]

/retest-required

Please review the full test history for this PR and help us cut down flakes.

[openshift-bot]

/retest-required

Please review the full test history for this PR and help us cut down flakes.

[haircommander]

/cherry-pick release-1.19

[haircommander]

(related to https://bugzilla.redhat.com/show_bug.cgi?id=2050399)

[openshift-cherrypick-robot]

@haircommander: #5704 failed to apply on top of branch "release-1.19":

Applying: oci: always reap conmon zombies
Applying: run make mockgen to fix unit tests
Using index info to reconstruct a base tree...
M	test/mocks/cmdrunner/cmdrunner.go
Falling back to patching base and 3-way merge...
Auto-merging test/mocks/cmdrunner/cmdrunner.go
CONFLICT (content): Merge conflict in test/mocks/cmdrunner/cmdrunner.go
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Patch failed at 0002 run make mockgen to fix unit tests
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".

In response to this:

/cherry-pick release-1.19

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