Improve benchmark script (ordinals#493)

- Fix file ownership
- Record elapsed time
- Save index.redb from each run

bin/benchmark

@@ -5,17 +5,22 @@ set -euxo pipefail
 rm -rf benchmark
 mkdir benchmark
 
+cd benchmark
+
 for HEIGHT_LIMIT in 100 250 500 1000 2000; do
-  sudo \
+  /usr/bin/time -o $HEIGHT_LIMIT.time sudo \
     CARGO_PROFILE_RELEASE_DEBUG=true \
     RUST_LOG=info \
     cargo flamegraph \
     --deterministic \
     --bin ord \
-    --output benchmark/$HEIGHT_LIMIT.svg \
+    --output $HEIGHT_LIMIT.svg \
     -- \
     --chain signet \
-    --data-dir benchmark \
+    --data-dir . \
     --height-limit $HEIGHT_LIMIT \
     index
+  sudo chown -n $UID $HEIGHT_LIMIT.svg
+  sudo chown -n $UID index.redb
+  mv index.redb $HEIGHT_LIMIT.redb
 done