Hide an adbconnection log behind VLOG(jdwp).

In moving to the new adbconnection jdwp-provider an error message that
was previously behind VLOG(jdwp) was moved to always being sent. This
could get rather spammy. The error message was that connecting to adbd
failed which can happen normally. Since the error message isn't very
helpful lower it to VLOG.

Test: build
Change-Id: Ief91105ffef6b4991efdb45c732acae7854ef88c
diff --git a/adbconnection/adbconnection.cc b/adbconnection/adbconnection.cc
index a0c9966..07fe9b6 100644
--- a/adbconnection/adbconnection.cc
+++ b/adbconnection/adbconnection.cc
@@ -539,7 +539,9 @@
         return false;
       }
     } else {
-      PLOG(ERROR) << "Can't connect to ADB control socket. Will retry.";
+      if (VLOG_IS_ON(jdwp)) {
+        PLOG(ERROR) << "Can't connect to ADB control socket. Will retry.";
+      }
 
       usleep(sleep_ms * 1000);