osd/ECBackend.cc: Fix double increment of num_shards_repaired stat

osd/ECBackend.cc: Fix double increment of num_shards_repaired stat

Commit https://github.com/ceph/ceph/commit/deffa8209f9c0bd300cfdb54d358402bfc6e41c6 refactored
ECBackend::handle_recovery_push for Crimson but accidentally duplicated the code that increments
the num_shards_repaired OSD statistic.

This caused one of the QA tests to fail because the stat reported twice as much repair work
had been completed than expected:

qa/standalone/scrub/osd-scrub-repair.sh: TEST_repair_stats_ec: test 26 = 13

Fixes: https://tracker.ceph.com/issues/64437
Signed-off-by: Bill Scales <bill_scales@uk.ibm.com>