[v4.2.0-rhel] Fix bug in sdnotifiy test

[cevich]

Commit 75c7a0d changed the variable name for a helper container image, but missed one reference. This causes the test to fail at the end. Fix this by using the correct variable name.

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Does this PR introduce a user-facing change?

None

[cevich]

@TomSweeneyRedHat not sure if this also afflicts any of the branches you're working on. I'm also unsure why I didn't notice it before 😞

[cevich]

Example of the sdnotify test failure and several knock-on failures caused by unexpected "extra" image presence.

output.txt

[lsm5]

LGTM

@TomSweeneyRedHat PTAL

[lsm5]

tiny nit: typo in commit message title sdnotifiy .