Speed up the /jobset overview pages a lot

Dependencies

• [2] TFVGX4JS Add an index to speed up the /project/<name> pages
• [*] N22GPKYT * Put info about logs / build products in the DB.
• [*] P5VJCT6U fix wrong comment
• [*] 6QRHXIM3 * Speed up the jobset index page. Especially the query to get the
• [*] 2I2ZX6JB * Make the "latest succeeded" query (used by the "latest" channel)

Change contents

• edit in src/sql/hydra.sql at line 528
  [2.81]

  [5.0]
  + create index IndexBuildsOnJobIsCurrent on Builds(project, jobset, job, isCurrent);
• edit in src/sql/hydra.sql at line 535
  [6.3040]

  [7.704]
  + create index IndexBuildsOnJobsetFinishedTimestamp on Builds(project, jobset, finished, timestamp);