refactor(vertexai): remove decommisioned generativeaionvertexai_gemini_token_count_advanced region tag

[Kef131]

Description

Fixes #
b/530681617

Region tag generativeaionvertexai_gemini_token_count_advanced shows no reference in devsite

Checklist

Testing

• I have tested this change on a live environment and verified it works as intended.
• Tests pass: mvn clean verify required
• Lint passes: mvn -P lint checkstyle:check required
• Static Analysis: mvn -P lint clean compile pmd:cpd-check spotbugs:check advisory only

Compliance & Style

• I have followed Sample Format Guide
• pom.xml parent set to latest shared-configuration
• Appropriate changes to README are included in PR
• This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample
• This sample adds a new Product API, and I updated the Blunderbuss issue/PR auto-assigner with the codeowners for this sample

Post-Approval Actions

• Please merge this PR for me once it is approved

[gemini-code-assist]

Code Review

This pull request removes documentation region tags from several Java snippet files. While decommissioning the token count snippet is expected, the reviewer notes that active region tags in QuestionAnswer.java and TextInput.java were accidentally removed as well. Restoring these tags is necessary to prevent breaking the associated public documentation pages.

[gemini-code-assist]

It appears that the region tag generativeaionvertexai_non_stream_text_basic was accidentally removed. The PR description only mentions decommissioning generativeaionvertexai_gemini_token_count_advanced. Removing this active region tag will break the Java code snippet on the public documentation page 'Generate Text With a Generative Model'. Please restore this tag.

Suggested change

	import com.google.cloud.vertexai.VertexAI;
	// [START generativeaionvertexai_non_stream_text_basic]
	import com.google.cloud.vertexai.VertexAI;

[gemini-code-assist]

Please restore the corresponding [END ...] region tag to avoid breaking the documentation page.

Suggested change

	}
	}
	// [END generativeaionvertexai_non_stream_text_basic]

[gemini-code-assist]

It appears that the region tag generativeaionvertexai_gemini_generate_from_text_input was accidentally removed. The PR description only mentions decommissioning generativeaionvertexai_gemini_token_count_advanced. Removing this active region tag will break the Java code snippet on the public documentation page 'Generate text from text-only input'. Please restore this tag.

Suggested change

	import com.google.cloud.vertexai.VertexAI;
	// [START generativeaionvertexai_gemini_generate_from_text_input]
	import com.google.cloud.vertexai.VertexAI;

[gemini-code-assist]

Please restore the corresponding [END ...] region tag to avoid breaking the documentation page.

Suggested change

	}
	}
	// [END generativeaionvertexai_gemini_generate_from_text_input]