Revert "hydra: bayfront: Stop submitting i586-gnu builds to the coordinator."

While things are still quite broken, the derivations themselves aren't
any more.

This reverts commit b1b0a47c9d.

hydra/bayfront.scm

@@ -1225,11 +1225,7 @@ add_header Content-Type text/plain;")))
                          "aarch64-linux"
                          "armhf-linux"
                          "powerpc64le-linux"
-                         ;; TODO: Re-enable once all revisions prior to
-                         ;; f56d37658e8dde7d53d1d3ae5a15c64cf0e8c7fc
-                         ;; have been processed
-                         ;; "i586-gnu"
-                         ))
+                         "i586-gnu"))
               (systems-and-targets
                (map (lambda (target)
                       (cons "x86_64-linux" target))