test: migrate form control usages to modern syntax (#28897)

Issue number: Internal

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## What is the current behavior?
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Several tests were still using the legacy form syntax.

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

- Migrated tests in `core`, `angular`, and `vue` to use the modern form
syntax (`react` did not have form controls).

I opted not to migrate `item/test/highlight` and `item/test/counter`
because those tests are going to be removed in the future once the
deprecate item APIs are removed.

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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## Other information

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screenshots of how the component looks before and after the change. -->

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Co-authored-by: ionitron <hi@ionicframework.com>
Co-authored-by: Maria Hutt <thetaPC@users.noreply.github.com>

core/src/components/datetime-button/test/buttons/index.html

@@ -18,7 +18,7 @@
       </ion-header>
       <ion-content>
         <ion-item>
-          <ion-input value="March 15, 2022 at 12:43 AM"></ion-input>
+          <ion-input aria-label="input" value="March 15, 2022 at 12:43 AM"></ion-input>
           <ion-datetime-button slot="end" id="default-button" datetime="default-datetime">
             <ion-icon color="primary" id="custom-date-button" slot="date-target" name="calendar"></ion-icon>
             <ion-icon color="primary" id="custom-time-button" slot="time-target" name="time"></ion-icon>