Cleanup std qualification and old bug citations

[StephanTLavavej]

• Drop _STD for _Is_finite, _Is_nan.
  • Added in Finish P0811R3 midpoint and lerp #1048. I noticed that they're _Ugly and we're in the std namespace when we call them, so according to our conventions they should be unqualified. (This was easy to miss because nearby code in <cmath> is in the global namespace, requiring _STD.)
• Remove unnecessary std:: qualification.
  • I found tests in std that were using namespace std; yet qualifying things.
• Use STD qualification in tr1.
  • We generally avoid modifying tr1, but I noticed that we accumulated a bit of inconsistency during maintenance. To make searching easier, I think we should consistently use its STD macro.
• Fix comment typo.
  • This was presumably in the original bug title, but searching is important.
• Avoid unintentional GH bug citations.
  • These were activating hover cards.
• Search-and-replace DevDiv#number to DevDiv-number.
• Search-and-replace Dev10#number to Dev10-number.
• Search-and-replace DDB#number to DDB-number.
  • All for consistency with our autolink-style citations (and to avoid #number although these weren't activating hover cards).
• Search and replace DevDiv2 #number to DevDiv-number.
  • More consistency, and to reduce confusion (now we're consistent about referring to "New TFS" as DevDiv, or Dev11 in directories).
• Manually fix bug citation.
  • I verified that this was the "DevDiv2/DevDiv" database, aka "DevDiv-number", aka "Dev11", aka "New TFS", and not DDB (aka "Dev09", aka "DevDiv Bugs" in Product Studio).