fix: leverage codex_utils_cargo_bin() in codex-rs/core/tests/suite (#8887)

This eliminates our dependency on the `escargot` crate and better
prepares us for Bazel builds: https://github.com/openai/codex/pull/8875.

codex-rs/Cargo.lock

@@ -1302,7 +1302,6 @@ dependencies = [
  "dunce",
  "encoding_rs",
  "env-flags",
- "escargot",
  "eventsource-stream",
  "futures",
  "http 1.3.1",
@@ -2810,17 +2809,6 @@ version = "3.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dea2df4cf52843e0452895c455a1a2cfbb842a1e7329671acf418fdc53ed4c59"
 
-[[package]]
-name = "escargot"
-version = "0.5.15"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "11c3aea32bc97b500c9ca6a72b768a26e558264303d101d3409cf6d57a9ed0cf"
-dependencies = [
- "log",
- "serde",
- "serde_json",
-]
-
 [[package]]
 name = "event-listener"
 version = "5.4.0"