refactor: read measurements from the local tree

The site compiles the index and the SQLite files from measurements/
instead of a pinned clone. The pin, the sync script, the CI clone steps,
the freshness area and its refresh handler are gone. core_probe --record
writes into measurements/ of the checkout by default, and a test fails
when a line or data file HEAD holds changed or vanished.

.github/workflows/validate.yml

@@ -29,7 +29,7 @@ on:
       - "database.json"
       - "release.json"
       - "derivable.json"
-      - "measurements-pin.json"
+      - "measurements/**"
       - "website/**"
   # Spelled out twice because the workflow parser reads no YAML anchor. A test
   # holds the two lists equal.
@@ -54,7 +54,7 @@ on:
       - "database.json"
       - "release.json"
       - "derivable.json"
-      - "measurements-pin.json"
+      - "measurements/**"
       - "website/**"
 
 permissions:
@@ -259,21 +259,11 @@ jobs:
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
-      # The measurement records at their pin, as deploy-site.yml reads them:
-      # the pages and the schema check read the same lines.
-      - name: Clone the measurements at their pin
-        run: |
-          repo=$(python -c "import json; print(json.load(open('measurements-pin.json'))['repo'])")
-          commit=$(python -c "import json; print(json.load(open('measurements-pin.json'))['commit'])")
-          git init -q .cache/measurements
-          git -C .cache/measurements fetch -q --depth 1 "$repo" "$commit"
-          git -C .cache/measurements checkout -q --detach "$commit"
-
       # The pages are gitignored, and the tests that read them fail
       # in CI without it. The suite runs whatever this step returned, so a
       # generator that stops still leaves every other test reporting.
       - name: Generate the site
-        run: python scripts/generate_site.py --require-measurements
+        run: python scripts/generate_site.py
 
       - name: Run test suite
         if: ${{ !cancelled() }}