feat(input): change fill default on ionic theme (#29789)

Issue number: internal

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

- Now the fill option default value is outline when using the Ionic
theme.
- Updated snapshots.

## 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. -->

- [Input Fill
Sample](https://ionic-framework-9fbgwzxss-ionic1.vercel.app/src/components/input/test/fill?ionic:theme=ionic)

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Co-authored-by: ionitron <hi@ionicframework.com>

core/src/components/input/input.tsx

@@ -492,6 +492,17 @@ export class Input implements ComponentInterface {
     return typeof this.value === 'number' ? this.value.toString() : (this.value || '').toString();
   }
 
+  private getFill(): string | undefined {
+    const theme = getIonTheme(this);
+    const { fill } = this;
+
+    if (theme === 'ionic' && fill === undefined) {
+      return 'outline';
+    }
+
+    return fill;
+  }
+
   private getLabelPlacement() {
     const theme = getIonTheme(this);
     const { el, labelPlacement } = this;
@@ -790,9 +801,10 @@ export class Input implements ComponentInterface {
   }
 
   render() {
-    const { disabled, fill, readonly, inputId, el, hasFocus, clearInput, inputClearIcon } = this;
+    const { disabled, readonly, inputId, el, hasFocus, clearInput, inputClearIcon } = this;
     const theme = getIonTheme(this);
     const value = this.getValue();
+    const fill = this.getFill();
     const size = this.getSize();
     const shape = this.getShape();
     const inItem = hostContext('ion-item', this.el);