KUDU-3318 [fs] Add size limit for log block container metadata

In some cases, log block container's data file is very small
after punching hole, while metadata file is relatively large
because it contains many CREATE-DELETE pairs. LBM reclaims
both .data and corresponding .metadata container files when
the .data container file becomes full (i.e. reaches its size
or block count threshold).
So, the .metadata container file might grow without any limit
before the .data container becomes full.
This patch adds a size limit for log block container's metadata,
taking it into account while determining the container's 'full'
condition. That gives the LBM an opportunity to reclaim the disk
space once the container becomes full.

Change-Id: I12513abf2e45f7bdf091142c31f50d650b6f0cfc
Reviewed-on: http://gerrit.cloudera.org:8080/17837
Tested-by: Kudu Jenkins
Reviewed-by: Alexey Serbin <aserbin@cloudera.com>
Reviewed-by: Andrew Wong <awong@cloudera.com>
4 files changed