tracing: Log to stderr, and drop timestamps

This matches bootc's setup (without the journal integration for now
as we don't strictly need it).

But specifically this fixes setting `RUST_LOG` and having that
break the monitor-status JSON stream:
bootc-dev#86 (comment)

Signed-off-by: Colin Walters <[email protected]>

Author: cgwalters

crates/kit/src/main.rs

@@ -154,7 +154,14 @@ fn install_tracing() {
     use tracing_subscriber::prelude::*;
     use tracing_subscriber::EnvFilter;
 
-    let fmt_layer = fmt::layer().with_target(false).with_writer(std::io::stderr);
+    let format = fmt::format()
+        .without_time()
+        .with_target(false)
+        .compact();
+
+    let fmt_layer = fmt::layer()
+        .event_format(format)
+        .with_writer(std::io::stderr);
     let filter_layer = EnvFilter::try_from_default_env()
         .or_else(|_| EnvFilter::try_new("info"))
         .unwrap();