Delete unused types for Mistral non-streaming requests (#38758)

Confusing to have these interspersed with the streaming request types

Release Notes:

- N/A

crates/mistral/src/mistral.rs

@@ -267,24 +267,6 @@ pub struct FunctionDefinition {
     pub parameters: Option<Value>,
 }
 
-#[derive(Debug, Serialize, Deserialize)]
-pub struct CompletionRequest {
-    pub model: String,
-    pub prompt: String,
-    pub max_tokens: u32,
-    pub temperature: f32,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub prediction: Option<Prediction>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub rewrite_speculation: Option<bool>,
-}
-
-#[derive(Clone, Deserialize, Serialize, Debug)]
-#[serde(tag = "type", rename_all = "snake_case")]
-pub enum Prediction {
-    Content { content: String },
-}
-
 #[derive(Debug, Serialize, Deserialize)]
 #[serde(rename_all = "lowercase")]
 pub enum ToolChoice {
@@ -397,21 +379,6 @@ pub struct FunctionContent {
     pub arguments: String,
 }
 
-#[derive(Serialize, Deserialize, Debug)]
-pub struct CompletionChoice {
-    pub text: String,
-}
-
-#[derive(Serialize, Deserialize, Debug)]
-pub struct Response {
-    pub id: String,
-    pub object: String,
-    pub created: u64,
-    pub model: String,
-    pub choices: Vec<Choice>,
-    pub usage: Usage,
-}
-
 #[derive(Serialize, Deserialize, Debug)]
 pub struct Usage {
     pub prompt_tokens: u64,
@@ -419,13 +386,6 @@ pub struct Usage {
     pub total_tokens: u64,
 }
 
-#[derive(Serialize, Deserialize, Debug)]
-pub struct Choice {
-    pub index: u32,
-    pub message: RequestMessage,
-    pub finish_reason: Option<String>,
-}
-
 #[derive(Serialize, Deserialize, Debug)]
 pub struct StreamResponse {
     pub id: String,