diamond: keep only current day's logs when running in labs

Further relieve pressure on the default /var which is only 2G

Change-Id: I8796373ae932cf85a5f6d33f7885c9a1c3f7a06a
diamond: Make ensure => absent work

Otherwise collectors with ensure => absent set are not removed,
and in fact are added if they aren't already present.

Change-Id: I121cd2023cbd46dc0edc9a645f0428344763260b
Merge changes I121cd202,I8796373a into production

* changes:
  diamond: Make ensure => absent work
  diamond: keep only current day's logs when running in labs