client: Address misc comments

client: Address misc comments

Removed ifdef for a failure we encountered during rebase against
case sensitive feature
-https://github.com/ceph/ceph/pull/61137#discussion_r2006324762w

Add debug dout when entering WriteEncMgr::read
-https://github.com/ceph/ceph/pull/61137#discussion_r2008140457

Remove FILE_RD mark_caps_dirty
-https://github.com/ceph/ceph/pull/61137#discussion_r2008192250

Add comment to various lines
-https://github.com/ceph/ceph/pull/61137#discussion_r2006301120
-https://github.com/ceph/ceph/pull/61137#discussion_r2006247613
-https://github.com/ceph/ceph/pull/61137#discussion_r2006251232

During write_success mark FILE_WR as dirty
-https://github.com/ceph/ceph/pull/61137#discussion_r2008210365

Signed-off-by: Christopher Hoffman <choffman@redhat.com>