Don't duplicate the autopkgtest log

* Reduce the per-test run <timestamp>.log files to the debci metadata
  (triggers, package versions, package diffs, overall result), as the actual
  autopkgtest log is now kept in data/*/autopkgtest/. This avoids
  duplicating the log contents.
* app.js: In the per-package test list, also add link to latest autopkgtest
  log.