Backport: fix: Azure DeepSeek structured output returns JSON in reasoning with empty text

[github-actions]

This is an automated backport of #17244 to the release-v6.0 branch. FYI @R-Taneja
This backport has conflicts that need to be resolved manually.

git cherry-pick output

Auto-merging packages/azure/src/azure-openai-provider.test.ts
Auto-merging packages/azure/src/azure-openai-provider.ts
Auto-merging packages/deepseek/src/chat/convert-to-deepseek-chat-messages.ts
Auto-merging packages/deepseek/src/chat/deepseek-chat-language-model.test.ts
CONFLICT (content): Merge conflict in packages/deepseek/src/chat/deepseek-chat-language-model.test.ts
Auto-merging packages/deepseek/src/chat/deepseek-chat-language-model.ts
Auto-merging packages/deepseek/src/chat/deepseek-chat-options.ts
error: could not apply 49ae04db3c... fix: Azure DeepSeek structured output returns JSON in reasoning with empty text (#17244)
hint: After resolving the conflicts, mark them with
hint: "git add/rm <pathspec>", then run
hint: "git cherry-pick --continue".
hint: You can instead skip this commit with "git cherry-pick --skip".
hint: To abort and get back to the state before "git cherry-pick",
hint: run "git cherry-pick --abort".
hint: Disable this message with "git config set advice.mergeConflict false"

[github-actions]

⚠️ Backport to release-v5.0 created but has conflicts: #17255

[github-actions]

🚀 Published in:

Package	Version
@ai-sdk/amazon-bedrock	4.0.136 github npm
@ai-sdk/azure	3.0.90 github npm
@ai-sdk/deepseek	2.0.49 github npm
@ai-sdk/google	3.0.93 github npm
@ai-sdk/google-vertex	4.0.161 github npm