ref: drop unreachable upstream-fetcher references and fix classify-one cache path

The Node server's read path now goes through ~/.cache/webi/legacy/ only
(see #1075). A handful of supporting tools and tests still carried
references to the obsolete upstream-fetcher modules and the old
year-month cache layout. Update them in place; the actual deletion of
the orphaned modules follows in #1076.

- _webi/classify-one.js — read from ~/.cache/webi/legacy/<pkg>.json
  instead of ../_cache/<yearMonth>/<pkg>.json.
- _webi/builds-cacher-test.js — drop the bc.freshenRandomPackage(...)
  call; the freshener was removed when fetching went away.
- _webi/builds.js — drop the //Releases: Releases stub comment.
- _webi/lint-builds.js — drop two now-unused require()s.
- _webi/test.js — adjust a single reference to the post-cleanup shape.

_webi/test.js

@@ -49,7 +49,7 @@ var baseurl = 'https://webinstall.dev';
 var maxLen = 0;
 console.info('');
 console.info('Has the necessary files?');
-['README.md', 'releases.js', 'install.sh', 'install.ps1']
+['README.md', 'install.sh', 'install.ps1']
   .map(function (node) {
     maxLen = Math.max(maxLen, node.length);
     return node;