Fix some broken indices

These indices basically did nothing since they put "id" first.

In particular this makes /job/.../all much faster.

src/sql/upgrade-68.sql

@@ -0,0 +1,5 @@
+drop index IndexBuildsOnJobsetIdFinishedId;
+create index IndexBuildsOnJobsetIdFinishedId on Builds(jobset_id, job, finished, id DESC);
+
+drop index IndexFinishedSuccessfulBuilds;
+create index IndexFinishedSuccessfulBuilds on Builds(jobset_id, job, finished, buildstatus, id DESC) where buildstatus = 0 and finished = 1;