Fix spacing in error logs for handshake timeout and idle network detection.

Without the space error messages looked like
`Client Error: QUIC_HANDSHAKE_TIMEOUT Detailed Error: Handshake timeout expired after 35696586us. Timeout:10snum_undecryptable_packets: 0 {}`

Protected by n/a logging output.

PiperOrigin-RevId: 578528813

quiche/quic/core/quic_connection.cc

diff --git a/quiche/quic/core/quic_connection.cc b/quiche/quic/core/quic_connection.cc
index b8de330..f926c4f 100644
--- a/quiche/quic/core/quic_connection.cc
+++ b/quiche/quic/core/quic_connection.cc
@@ -6299,7 +6299,7 @@
       ". Timeout:",
       idle_network_detector_.handshake_timeout().ToDebuggingValue());
   if (perspective() == Perspective::IS_CLIENT && version().UsesTls()) {
-    absl::StrAppend(&error_details, UndecryptablePacketsInfo());
+    absl::StrAppend(&error_details, " ", UndecryptablePacketsInfo());
   }
   QUIC_DVLOG(1) << ENDPOINT << error_details;
   CloseConnection(QUIC_HANDSHAKE_TIMEOUT, error_details,
@@ -6316,7 +6316,7 @@
       idle_network_detector_.idle_network_timeout().ToDebuggingValue());
   if (perspective() == Perspective::IS_CLIENT && version().UsesTls() &&
       !IsHandshakeComplete()) {
-    absl::StrAppend(&error_details, UndecryptablePacketsInfo());
+    absl::StrAppend(&error_details, " ", UndecryptablePacketsInfo());
   }
   QUIC_DVLOG(1) << ENDPOINT << error_details;
   const bool has_consecutive_pto =