prod-lon: reduce number of dopplers to 54
prod-lon: reduce number of dopplers to 54

much of a dopplers workload has been moved to log-cache nodes

alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf