build: switch governor to system time

We can make this test only by adding a feature for it and checking, but it didn't seem immediately worth it to me. Ping me if you want me to change it.

Shaves about 15-20% off of a j2 test run, because we spent about 200ms on every one of the 500 tests against the server just initializing the governor clock.

Cargo.lock

@@ -2816,7 +2816,6 @@ dependencies = [
  "nonzero_ext",
  "parking_lot",
  "portable-atomic",
- "quanta",
  "rand 0.9.2",
  "smallvec",
  "spinning_top",

Cargo.toml

@@ -81,7 +81,7 @@ ed25519-dalek = { version = "2.1", features = ["pkcs8"] }
 foca = { version = "1", features = ["bincode-codec", "tracing"] }
 futures = "0.3"
 futures-util = "0.3"
-governor = "0.10"
+governor = { version = "0.10", default-features = false, features = ["std", "dashmap", "jitter"] }
 h3 = "0.0.8"
 h3-quinn = "0.0.10"
 hex = "0.4"