Avoid erroring out when unable to remove or parse logical rewrite files to save checkpoint work

Hi,

Currently the server is erroring out when unable to remove/parse a
logical rewrite file in CheckPointLogicalRewriteHeap wasting the
amount of work the checkpoint has done and preventing the checkpoint
from finishing. This is unlike CheckPointSnapBuild does for snapshot
files i.e. it just emits a message at LOG level and continues if it is
unable to parse or remove the file. Attaching a small patch applying
the same idea to the mapping files.

Thoughts?

Regards,
Bharath Rupireddy.