openai: Don't send prompt_cache_key for OpenAI-compatible models (#36231)

Some APIs fail when they get this parameter

Closes #36215

Release Notes:

- Fixed OpenAI-compatible providers that don't support prompt caching
and/or reasoning

crates/language_models/src/provider/cloud.rs

@@ -941,6 +941,7 @@ impl LanguageModel for CloudLanguageModel {
                     request,
                     model.id(),
                     model.supports_parallel_tool_calls(),
+                    model.supports_prompt_cache_key(),
                     None,
                     None,
                 );