chore(ci): remove ng12-15 apps, add ng16-17 for stencil nightlies (#28945)

Issue number: Internal

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## What is the current behavior?
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The Stencil nightlies are still attempting to run old Angular test apps
and does not test ng16/17

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

- Removed ng12-15 test apps
- Added ng16-17 test apps

I opted to remove ng14-15 because we are in the process of dropping
support for it in Ionic 8.

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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## Other information

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Author: liamdebeasi

.github/workflows/stencil-nightly.yml

@@ -150,7 +150,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        apps: [ng12, ng13, ng14, ng15]
+        apps: [ng16, ng17]
     needs: [build-angular, build-angular-server]
     runs-on: ubuntu-latest
     steps: