Revert "Update the package derivations table in a transaction"

This is already in a transaction.

This reverts commit 1da2a09cfb.

guix-data-service/jobs/load-new-guix-revision.scm

@@ -2617,14 +2617,11 @@ SELECT store_path FROM derivation_source_files WHERE id = $1"
                   #t "debug: importing channel news not supported\n")
                  #t))
 
-           (with-postgresql-transaction
-            conn
-            (lambda (conn)
            (update-package-derivations-table
             conn
             git-repository-id
             (fibers-force guix-revision-id-promise)
-               commit)))
+            commit)
            (with-time-logging "updating builds.derivation_output_details_set_id"
              (update-builds-derivation-output-details-set-id
               conn