Fix some looping_call calls which were broken in #3604

It turns out that looping_call does check the deferred returned by its
callback, and (at least in the case of client_ips), we were relying on this,
and I broke it in #3604.

Update run_as_background_process to return the deferred, and make sure we
return it to clock.looping_call.

1 files changed, 1 insertions, 0 deletions

diff --git a/changelog.d/3610.feature b/changelog.d/3610.feature
new file mode 100644
index 0000000000..77a294cb9f
--- /dev/null
+++ b/changelog.d/3610.feature
@@ -0,0 +1 @@
+Add metrics to track resource usage by background processes