Workers’ compensation — Temporary partial disability — Judge of compensation claims erred in denying TPD benefits based on medical evidence that claimant’s ailment was never related to her employment where compensability was established by operation of section 440.20(4) during pay-and-investigate period — Error was harmless where claimant failed to satisfy prima facie burden which also included proof that workplace injury caused a reduction of wages below 80% of claimant’s pre-injury average weekly wage