NAS-138810 / 26.04 / Update truenas_verify to not report nfs.conf.d (#952)

* Exclude /etc/nfs.conf.d.   This directory is removed by nfs.conf.mako.

* Add exception handling for os.unlink when processing objects that
are aleady missing.

scale_build/image/mtree.py

@@ -26,6 +26,7 @@ ETC_FILES_TO_REMOVE = [
     'etc/krb5.conf',
     'etc/mailname',
     'etc/motd',
+    'etc/nfs.conf.d',
     'etc/nscd.conf',
     'etc/resolv.conf',
     'etc/avahi/avahi-daemon.conf',
@@ -136,7 +137,12 @@ def generate_mtree(target_root_dir, version):
     # we replace when we etc.generate. If they're not required for
     # first boot, then remove from update file.
     for file in ETC_FILES_TO_REMOVE:
-        os.unlink(os.path.join(target_root_dir, file))
+        try:
+            os.unlink(os.path.join(target_root_dir, file))
+        except FileNotFoundError:
+            # We want to avoid failing the build if the object is
+            # aleady removed.  Possibly time to update the list.
+            pass
 
     # Some files and/or directories get their permission mode changed
     # after install.  We preemptively make those mode changes here