fix: update showcase company data

[abdallahshaban557]

Description of what this PR is changing or adding, and why:

Update the showcase company logos in the main /showcase page.

Issues fixed by this PR (if any):

PRs or commits this PR depends on (if any):

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[gemini-code-assist]

Code Review

This pull request removes two SVG files, deletes Bytedance from the showcase companies list, and updates the card image path for the Karaca showcase to use the company logo. The reviewer correctly pointed out that using the company logo as the card image might cause layout or scaling issues on the showcase page due to aspect ratio requirements, and recommended using a properly proportioned card image instead.

[flutter-website-bot]

Staged preview of the updated docs.flutter.dev site (updated for commit 31c4c30):

https://flutter-docs-prod--docs-pr13535-fix-images-showcases-5pgqpf8z.web.app

[flutter-website-bot]

Staged preview of the updated flutter.dev site (updated for commit 31c4c30):

https://flutter-dev-230821--www-pr13535-fix-images-showcases-fewk5xu3.web.app

[lamek]

LGTM