fix(textarea): respect rows prop by adjusting min-height in the ionic theme (#30957)

Issue number: resolves internal

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## What is the current behavior?
- The `rows` attribute is not respected in `ion-textarea` when lower
than 3. Some paddings and margins were applied in incorrect places in
the `ionic` theme.

## What is the new behavior?
- The ionic theme has the following changes:
- `.textarea-size-*` classes stopped forcing the `min-height` allowing
`rows` to adjust the height
- Added an end-to-end test file `textarea.e2e.ts` to verify that the
`rows` attribute is respected across different values, sizes, and with
auto-grow enabled.
- Introduced a new HTML test page (`index.html`) for visual/manual
testing of `ion-textarea` with different `rows` and `size` combinations,
and with auto-grow enabled.

## Does this introduce a breaking change?
- [ ] Yes
- [x] No

## Other information

- [Textarea:
Autogrow](https://ionic-framework-git-rou-12443-v4-ionic1.vercel.app/src/components/textarea/test/autogrow?ionic:theme=ionic)
- [Textarea:
Basic](https://ionic-framework-git-rou-12443-v4-ionic1.vercel.app/src/components/textarea/test/basic?ionic:theme=ionic)
- [Textarea:
Rows](https://ionic-framework-git-rou-12443-v4-ionic1.vercel.app/src/components/textarea/test/rows?ionic:theme=ionic)
- [Textarea:
Size](https://ionic-framework-git-rou-12443-v4-ionic1.vercel.app/src/components/textarea/test/size?ionic:theme=ionic)
- [Textarea:
Shape](https://ionic-framework-git-rou-12443-v4-ionic1.vercel.app/src/components/textarea/test/shape?ionic:theme=ionic)

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