chore(ci): remove stencil v4 nightly workflow (#27708)

Issue number: N/A

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## What is the current behavior?
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We have a workflow that is no longer needed (that I wrote 🙃) 

## What is the new behavior?
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this PR. -->

remove the stencil v4 nightly workflow following the stencil v4 release
on 2023.06.26

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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and migration path for existing applications below. -->


## Other information

I'll have to take a look at the Actions tab at GitHub after this is
merged. I may have to do some manual cleanup (deleting workflow runs)
once this file is no longer in the repo.
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screenshots of how the component looks before and after the change. -->