Remove duplicate span.end() causing log pollution. (#4497)

Author: snehashah16

google-cloud-clients/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerImpl.java

@@ -1291,7 +1291,6 @@ public <T> T run(TransactionCallable<T> callable) {
         // We also do this unconditionally in case a user has modified the flag when the transaction
         // was running.
         hasPendingTransaction.remove();
-        span.end();
       }
     }
 
@@ -2627,7 +2626,6 @@ public void close(@Nullable String message) {
       if (stream != null) {
         stream.close(message);
       }
-      span.end();
     }
 
     @Override