As part of this work, removing SDDbgValue::clearIsEmitted originally added for
dbg.addr in 045c67769d7fe577fc38cccb6fb40fd814437447 was attempted, but it
appears some tests for DBG_INSTR_REF now depend on that behaviour as well, so
it was kept and comments were updated instead.
Part of dbg.addr removal
Discussed in https://discourse.llvm.org/t/what-is-the-status-of-dbg-addr/62898
Depends on D144799