Image generation model update pt4

[XrossFox]

Description

Deletes unused image generation examples (raw reference, scribble control type, and style reference) and updates the corresponding tests.

Fixes b/555332289

Checklist

Testing

• I have tested this change on a live environment and verified it works as intended.

Compliance & Style

• I have followed the Sample Guidelines.
• The README is updated with all relevant information (if applicable).
• If this PR adds a new sample directory: I updated the CODEOWNERS file.

---

Post-Approval Actions

• Please merge this PR for me once it is approved

[gemini-code-assist]

Code Review

This pull request removes three image generation customization sample files (raw reference, scribble control type, and style reference) along with their corresponding test cases and imports in test_image_generation.py. I have no feedback to provide as there are no review comments.

[angelcaamal]

I didn't find any references to these removed samples, LGTM!

[snippet-bot]

Here is the summary of changes.

You are about to delete 3 region tags.

• genai/image_generation/imggen_raw_reference_with_txt_img.py:17, tag googlegenaisdk_imggen_raw_reference_with_txt_img
• genai/image_generation/imggen_scribble_ctrl_type_with_txt_img.py:17, tag googlegenaisdk_imggen_scribble_ctrl_type_with_txt_img
• genai/image_generation/imggen_style_reference_with_txt_img.py:17, tag googlegenaisdk_imggen_style_reference_with_txt_img

---

This comment is generated by snippet-bot.
If you find problems with this result, please file an issue at:
https://github.com/googleapis/repo-automation-bots/issues.
To update this comment, add snippet-bot:force-run label or use the checkbox below:

• Refresh this comment