Allow "has draft inlines?" queries to overheat

Summary:
Ref T13513. If your 10 most recently authored inlines have all been deleted, these queries can fail by overheating. This is silly and probably rarely happens outside of development.

For now, just let them overheat. This may create a false negative (incorrect "no draft" signal when the real condition is "drafts, but 10 most recent comments were deleted"). This could be sorted out later with a query mode like "executeAny()", perhaps.

Test Plan:
  - Created and deleted 10 inlines.
  - Submitted comments.
  - Before: overheating fatal during draft flag generation.
  - After: clean submission.

Maniphest Tasks: T13513

Differential Revision: https://secure.phabricator.com/D21274

src/applications/differential/engine/DifferentialRevisionDraftEngine.php

@@ -11,6 +11,7 @@ final class DifferentialRevisionDraftEngine
       ->setViewer($viewer)
       ->withRevisionPHIDs(array($revision->getPHID()))
       ->withPublishableComments(true)
+      ->setReturnPartialResultsOnOverheat(true)
       ->setLimit(1)
       ->execute();
 

src/applications/diffusion/engine/DiffusionCommitDraftEngine.php

@@ -11,6 +11,7 @@ final class DiffusionCommitDraftEngine
       ->setViewer($viewer)
       ->withCommitPHIDs(array($commit->getPHID()))
       ->withPublishableComments(true)
+      ->setReturnPartialResultsOnOverheat(true)
       ->setLimit(1)
       ->execute();