[risk=low][no ticket] clean up computeRenewalDisplayDates (#6283)
[risk=low][no ticket] clean up computeRenewalDisplayDates (#6283)


all-of-us/workbench,all-of-us/workbench,all-of-us/workbench,all-of-us/workbench,all-of-us/workbench,all-of-us/workbench,all-of-us/workbench,all-of-us/workbench,all-of-us/workbench