apps: silence or downgrade some logs in the client

When doing a large amount of requests, quiche-client is quite chatty,
even though I only care about the final report (and the response data).
diff --git a/tools/apps/src/lib.rs b/tools/apps/src/lib.rs
index e56f933..db28030 100644
--- a/tools/apps/src/lib.rs
+++ b/tools/apps/src/lib.rs
@@ -286,8 +286,6 @@
         let mut reqs_done = 0;
 
         for req in self.reqs.iter_mut().skip(self.reqs_sent) {
-            info!("sending HTTP request {:?}", req.request_line);
-
             match conn.stream_send(
                 self.stream_id,
                 req.request_line.as_bytes(),
@@ -306,6 +304,8 @@
                 },
             };
 
+            debug!("sending HTTP request {:?}", req.request_line);
+
             req.stream_id = Some(self.stream_id);
             req.response_writer =
                 make_writer(&req.url, target_path, req.cardinal);
@@ -667,8 +667,6 @@
         let mut reqs_done = 0;
 
         for req in self.reqs.iter_mut().skip(self.reqs_sent) {
-            info!("sending HTTP request {:?}", req.hdrs);
-
             let s = match self.h3_conn.send_request(
                 conn,
                 &req.hdrs,
@@ -683,12 +681,19 @@
                     break;
                 },
 
+                Err(quiche::h3::Error::StreamBlocked) => {
+                    debug!("stream is blocked, retry later...");
+                    break;
+                },
+
                 Err(e) => {
                     error!("failed to send request {:?}", e);
                     break;
                 },
             };
 
+            debug!("sending HTTP request {:?}", req.hdrs);
+
             req.stream_id = Some(s);
             req.response_writer =
                 make_writer(&req.url, target_path, req.cardinal);
@@ -713,7 +718,7 @@
         loop {
             match self.h3_conn.poll(conn) {
                 Ok((stream_id, quiche::h3::Event::Headers { list, .. })) => {
-                    info!(
+                    debug!(
                         "got response headers {:?} on stream id {}",
                         list, stream_id
                     );