Currently, when we calculate the number of deactivated segments
in test_commitlog_delete_when_over_disk_limit, we only count the
segments that were active during the first flush. However, during
the test, there may have been more than one flush, and a segment
could have been created between them. This segment would sometimes
get deactivated and even destroyed, and as a result, the count of
destroyed segments would appear larger than the count of deactivated
ones.
This patch fixes this behavior by accounting for all segments that
were active during any flush instead of just segments active during
the first flush.
Fixes#10527
(cherry-picked from commit 39a8f4310d)
Closesscylladb/scylladb#19706