function insertSampleJobs() {
  var rows = [];
  for (var i = 0; i < ROW_COUNT; ++i) {
    var job = lf.testing.hrSchemaSampleData.generateSampleJobData(db);
    job.setId('jobId' + i.toString());
    rows.push(job);
  }
  return db.insert().into(j).values(rows).exec();
}
Inserts sample Job rows in the Jobs table.
@return {!IThenable}