treewide: enable pure Go by default

Pure can be safely enabled by default. For those targets which need cgo,
we can set `pure = "off"` on the go_binary or go_test.

This simplifies transitions, and makes the files/files_cc distinction
obsolete.

Change-Id: Ic1a985e7d347a7222f55735c1ee2016e8a7e1c65
Reviewed-on: https://review.monogon.dev/c/monogon/+/4158
Tested-by: Jenkins CI
Reviewed-by: Tim Windelschmidt <tim@monogon.tech>
diff --git a/osbase/fsquota/BUILD.bazel b/osbase/fsquota/BUILD.bazel
index 0293e25..dba031f 100644
--- a/osbase/fsquota/BUILD.bazel
+++ b/osbase/fsquota/BUILD.bazel
@@ -26,7 +26,7 @@
 k_test(
     name = "ktest",
     cmdline = "ramdisk_size=51200",
-    files_cc = {
+    files = {
         "/mkfs.xfs": "@xfsprogs//:mkfs",
     },
     tester = ":fsquota_test",