FF-3594 Decrease default poller jitter (#101)

Our default jitter value was migrated from Python SDK. However, once
we decreased the default poller interval, this made jitter value too
high.

With 30s poll interval and 30s jitter, requests are made every 0–30
seconds (with average at 15s). That just doesn’t make much sense.

Decrease jitter value down to 3s, so it polls every 27–30s (avg
28.5s).

Author: rasendubi

eppo_core/src/poller_thread.rs

@@ -30,7 +30,7 @@ impl PollerThreadConfig {
     /// Default value for [`PollerThreadConfig::interval`].
     pub const DEFAULT_POLL_INTERVAL: Duration = Duration::from_secs(30);
     /// Default value for [`PollerThreadConfig::jitter`].
-    pub const DEFAULT_POLL_JITTER: Duration = Duration::from_secs(30);
+    pub const DEFAULT_POLL_JITTER: Duration = Duration::from_secs(3);
 
     /// Create a new `PollerThreadConfig` using default configuration.
     pub fn new() -> PollerThreadConfig {