fix(spanner): end spans for read-write methods (googleapis#3629)

Author: harshachinta

google-cloud-spanner/src/main/java/com/google/cloud/spanner/DatabaseClientImpl.java

@@ -294,6 +294,8 @@ public TransactionManager transactionManager(TransactionOption... options) {
  span.setStatus(e);
  span.end();
  throw e;
+ } finally {
+ span.end();
  }
  }
 

google-cloud-spanner/src/test/java/com/google/cloud/spanner/DatabaseClientImplTest.java

@@ -4006,7 +4006,10 @@ public void testTransactionManager_usesOptions() {
  when(pool.getSession()).thenReturn(session);
  TransactionOption option = mock(TransactionOption.class);
 
- DatabaseClientImpl client = new DatabaseClientImpl(pool, mock(TraceWrapper.class));
+ TraceWrapper traceWrapper =
+ new TraceWrapper(Tracing.getTracer(), OpenTelemetry.noop().getTracer(""), false);
+
+ DatabaseClientImpl client = new DatabaseClientImpl(pool, traceWrapper);
  try (TransactionManager ignore = client.transactionManager(option)) {
  verify(session).transactionManager(option);
  }