[clang] [clang] Stop reporting unresolved issues in `cxx_dr_status.html` (PR #78836)

[via cfe-commits]

cor3ntin wrote:

I am slightly concerned with this direction.
A lot of these issues are actually fully resolved and just haven't made it to an official list yet.

I would prefer that if we are fairly certain of the status of an issue we keep a version number (and if we are not, then we don't)

https://github.com/llvm/llvm-project/pull/78836