[iOS] Avoid Shape animation changing visibility

[jsuarezruiz]

Description of Change

When initializing a hidden Shape, the initial size is zero, which is then updated to the correct size here: https://github.com/xamarin/Xamarin.Forms/blob/f35ae07a0a8471d255f7a1ebdd51499e10e0a4cb/Xamarin.Forms.Platform.iOS/Shapes/ShapeRenderer.cs#L391

We avoid using the implicit animation doing the changes: https://github.com/xamarin/Xamarin.Forms/blob/f35ae07a0a8471d255f7a1ebdd51499e10e0a4cb/Xamarin.Forms.Platform.iOS/Shapes/ShapeRenderer.cs#L371 And with this PR what is done is to initialize the Shape with the expected size even when it is hidden. By changing the visibility, there is nothing to change.

Issues Resolved

• fixes #13018

API Changes

None

Platforms Affected

• iOS

Behavioral/Visual Changes

None

Before/After Screenshots

None

Testing Procedure

Launch Core Gallery and navigate to the issue 13018. Select one of the ellipses. If render the border shape without any animation, the test has passed (and we have the same behavior in all the platforms).

PR Checklist

• [ ] Targets the correct branch
• [ ] Tests are passing (or failures are unrelated)