remove lib.form.hetero-list.hetero-list

[car-roll]

See jenkinsci/jenkins#8418 (comment)

hetero-list adjunct was removed in jenkinsci/jenkins#8418
If this adjunct gets called, a large stack trace error should appear in the logs.

Testing done

Tested under a local instance using a github multibranch folder but have not been able to extract any errors and was able to generate an error. This PR + jenkinsci/branch-api-plugin#415

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6. Ensure you have provided tests - that demonstrates feature works or fixes the issue

[dwnusbaum]

@car-roll Does this work both before/after jenkinsci/jenkins#8418, or do we need to bump the minimum Jenkins version at the same time?

[car-roll]

@dwnusbaum ah you're right, I would probably need to bump.

[car-roll]

change was introduced in 2.422, chose the (soon-to-be) next LTS

[rsandell]

Weird though that instead of doing a quick backwards compatibility fix in core, all plugins needs to be fixed.