Delete OrderBy(...).First{OrDefault}(...) optimization (#36643)

Delete OrderBy(...).First{OrDefault}(...) optimization (#36643)

The optimization removes the O(n log n) cost of the OrderBy. But it can result in executing the predicate passed to First{OrDefault} more than in .NET Framework; it would always execute it n times, whereas previously it would execute it <= n times.  Developers have expressed concern about the change, in particular when using a relatively expensive predicate on a relatively short list, or when unadvisedly relying on side-effecting predicates.