remove duplicate element IDs on sign-in page
remove duplicate element IDs on sign-in page

- Fixes #7509

JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio