crimson/osd: make osd_op_params::at_version coherent with last log entry

crimson/osd: make osd_op_params::at_version coherent with last log entry

Before this commit we were doing something like:

1. initialize `at_version` with PG::projected_last_update`
   **incremented by one**.
2. produce a log entry at such version.
3. increment `at_version` for the sake of a further production
   that may never come.

The problem is `osd_op_params::at_version` is higher by one
than the last log entry which hurts at later stages of
`osd_op_params` processing (I was hit in the shared EC code
by the assertion in `PG::op_applied`).

This patch changes the algorithm to:

A. initialize `at_version` with PG::projected_last_update`
   **incremented by one**.
B. increment `at_version` for the sake of the very next production.
C. produce a log entry at this version.

Co-authored-by: Matan Breizman <mbreizma@redhat.com>
Signed-off-by: Radoslaw Zarzynski <rzarzyns@redhat.com>