fix(simple-combo): remove simple combo limitation

[Hristo313]

Closes #277

Checklist:

• check topic's TOC/menu and paragraph headings
• Include TOC topic labels in the topic content when it has a valuable update, is new, or is considered preview / beta
• link to other topics using ../relative/path.md
• at the References section at the end of the topic add links to topics, samples, etc
• reference API documentation instead of adding a section with API

• use valid component names - [Data] Grid, IgxSelectComponent, <igx-combo>
• use spell checker tool (VS Code, Grammarly, Microsoft Editor)
• add inline code blocks for the names of classes / tags / properties
• add language descriptor for the code blocks
• check if links function by running the check-api/mdx npm commands
• check if sample is working and fully visible in the topic
• check if sample is working and fully visible in the StackBlitz
• check if code blocks match the code in StackBlitz demo
• add or update meaningful llms.description metadata and run npm run check:llms-metadata

• follow SEO guidelines to fill topic's metadata (SEO guidelines)

• do not resolve requested changes (leave that to the reviewer)

[Copilot]

Pull request overview

Updates the Ignite UI for Angular Simple Combo documentation to remove an outdated “height sizing limitation” from the Known Issues section, aligning the docs with current styling capabilities.

Changes:

• Removed the outdated Known Issue about not being able to size the Simple Combo height (EN/JP/KR).
• Ensured the KR topic’s “Known Issues” list reflects the current set of documented limitations.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
docs/angular/src/content/kr/components/simple-combo.md	Removes outdated height-sizing limitation and updates the Known Issues list content.
docs/angular/src/content/jp/components/simple-combo.mdx	Removes outdated height-sizing limitation from Known Issues.
docs/angular/src/content/en/components/simple-combo.mdx	Removes outdated height-sizing limitation from Known Issues.

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