chore(config) rm tools.view_image (#22501)

## Summary
It appears this config flag has been broken/a noop for quite some time:
since https://github.com/openai/codex/pull/8850. Let's simplify and get
rid of this.

## Testing
- [x] Updated unit tests

codex-rs/app-server-protocol/src/protocol/v1.rs

@@ -228,7 +228,6 @@ pub struct Profile {
 #[serde(rename_all = "camelCase")]
 pub struct Tools {
     pub web_search: Option<bool>,
-    pub view_image: Option<bool>,
 }
 
 #[derive(Deserialize, Debug, Clone, PartialEq, Serialize, JsonSchema, TS)]