void writeData(Connection conn, TableName tn, long sizeInBytes) throws IOException {
    writeData(tn, sizeInBytes, Bytes.toBytes("q1"));
  }
Waits {@code timeout} milliseconds for the HBase quota table to exist.
hbase-server/src/test/java/org/apache/hadoop/hbase/quotas/SpaceQuotaHelperForTests.java