info: Reduce delay between messages

The info service takes a long time to populate its state after a restart, in
particular on production scale systems.

This patch reduces the delay between queries. The overall frequency is not
increased, but the delay between two queries is reduced to 100 ms (from 2, 5,
or 10 seconds, depending on the query). As these queries are relatively
light-weight, 100 ms should be plenty to keep the message passing overhead
down.

I request backport to 2.10 as we always have issues with our Nagios probes
after a restart.

Target: trunk
Request: 2.11
Request: 2.10
Require-notes: yes
Require-book: no
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: https://rb.dcache.org/r/7535/
(cherry picked from commit 9317083dcb67512cb72636b4802e152db55cd7fa)
info: Reduce safety limit to 50 ms

After reducing the DGA query separation to 100 ms, the DGA safety kick in and
limits the DGA frequency. This patch changes the safety limit to 50 ms (20 Hz).

Target: trunk
Request: 2.11
Request: 2.10
Require-notes: no
Require-book: no
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: https://rb.dcache.org/r/7540/
(cherry picked from commit 8c295eeec9da72895b1994d44eebff7b522edee7)
Merge pull request #1126 from gbehrmann/fix/2.10/rb7535

info: Reduce delay between messages