Add switch reason to verbose logging of SortAndSwitchConnection

while this is already logged when actually switching, knowing
why connections get sorted and evaluated may be useful.

BUG=None

Change-Id: I1449b0e1fb3624c04d7fb2730a05ffa7c7d1f37a
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/313100
Reviewed-by: Sameer Vijaykar <samvi@google.com>
Reviewed-by: Jonas Oreland <jonaso@webrtc.org>
Commit-Queue: Philipp Hancke <phancke@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#40521}

p2p/base/basic_ice_controller.cc

@@ -540,7 +540,8 @@ BasicIceController::SortAndSwitchConnection(IceSwitchReason reason) {
       });
 
   RTC_LOG(LS_VERBOSE) << "Sorting " << connections_.size()
-                      << " available connections";
+                      << " available connections due to: "
+                      << IceSwitchReasonToString(reason);
   for (size_t i = 0; i < connections_.size(); ++i) {
     RTC_LOG(LS_VERBOSE) << connections_[i]->ToString();
   }