scoutfs-tests: remove segment-cache-fwd-back-iter

The segment-cache-fwd-back-iter test only applied to populating the item
cache from segments, and we don't do that anymore.  The test can
be removed.

Signed-off-by: Zach Brown <zab@versity.com>

tests/golden/segment-cache-fwd-back-iter

@@ -1,3 +0,0 @@
-== create files
-== count allocations reading forwards
-== count allocations reading backwards

tests/sequence

@@ -6,7 +6,6 @@ simple-staging.sh
 simple-release-extents.sh
 offline-extent-waiting.sh
 simple-xattr-unit.sh
-segment-cache-fwd-back-iter.sh
 lock-refleak.sh
 lock-shrink-consistency.sh
 lock-pr-cw-conflict.sh

tests/tests/segment-cache-fwd-back-iter.sh

@@ -1,39 +0,0 @@
-#
-# We had some segment reading patterns that lead to excessive segment
-# reading if ops iterated over items in the opposite order that they're
-# sorted in segments.
-#
-# Let's make sure iterating over items in either directions causes the
-# item reading path to cache the items in the segments regardless of
-# which item caused the miss.
-#
-# We can use the count of item allocations as a proxy for the bad
-# behaviour.
-#
-
-t_require_commands mkdir touch stat cat
-
-DIR="$T_D0/dir"
-NR=3000
-
-t_quiet mkdir -p "$DIR"
-
-echo "== create files"
-for a in $(seq 1 $NR); do t_quiet touch $DIR/$a; done
-
-echo "== count allocations reading forwards"
-echo 3 > /proc/sys/vm/drop_caches
-for a in $(seq 1 $NR); do stat $DIR/$a > /dev/null; done
-FWD=$(t_counter item_alloc)
-echo "forward item allocations: $FWD" >> "$T_TMP.log"
-
-echo "== count allocations reading backwards"
-echo 3 > /proc/sys/vm/drop_caches
-for a in $(seq $NR -1 1); do stat $DIR/$a > /dev/null; done
-BWD=$(t_counter item_alloc)
-echo "backward item allocations: $BWD" >> "$T_TMP.log"
-if [ "$BWD" -gt "$((FWD * 5))" ]; then
-	echo "backward item iteration allocated $BWD > 5x forward $FWD"
-fi
-
-t_pass