Releases should not be parsed again every four weeks on their own

Problem

Drupal 7 parses a release once, and again only when its package changed (the local packages connector compares the file date) or when an administrator starts over with it. On 3.0.x the release storage offers the releases parsed more than four weeks ago as due for parsing again, and the drupal.org connector takes one of them whenever it is asked to parse without a release; the local packages connector falls back to the oldest parsed release the same way. On a site the size of localize.drupal.org that means parsing every release again, all the time, for nothing.

Proposed resolution

Remove the four-week refresh and the fallbacks: the parse handlers parse the release they are given, cron, the batch and drush pick the unparsed releases (#3621583), a changed package or start over resets the parse time. The refresh storage interface goes with it.

Tests

Drupal 7 first: the cron test of the local packages connector checks that further cron runs parse nothing while the packages stay the same. Ported into the 3.0.x cron test; the file system connector test sets its release explicitly instead of relying on the fallback.

LLM disclosure

LLM was used to find, diagnose explain and fix this issue. With human review.