Remove individual URL overrides for LLM service (#30290)

This PR removes the individual URL overrides for the LLM service.

We initially had `ZED_PREDICT_EDITS_URL` to allow for directing traffic
to the LLM Worker back when there was still the split of the
Collab-based LLM Service and the Cloudflare-based LLM Worker.

But now that all of the LLM functionality has been moved into the
Worker, we can just direct all traffic there.

Release Notes:

- N/A

crates/http_client/src/http_client.rs

@@ -231,7 +231,7 @@ impl HttpClientWithUrl {
         let base_api_url = match base_url.as_ref() {
             "https://zed.dev" => "https://llm.zed.dev",
             "https://staging.zed.dev" => "https://llm-staging.zed.dev",
-            "http://localhost:3000" => "http://localhost:8080",
+            "http://localhost:3000" => "http://localhost:8787",
             other => other,
         };