Add bench_streamer feature to inhibit building solana-bench-streamer by default

This program is not currently used in any automation and is fairly slow
to build.  Disabling it by default will speed incremental builds.

ci/test-stable.sh

@@ -23,7 +23,11 @@ if [[ $(ulimit -n) -lt $maxOpenFds ]]; then
   }
 fi
 
-_ cargo build --all --verbose
+# bench_streamer is enabled by default to speed up dev builds, enable it
+# explicitly here to ensure it still compiles
+FEATURES=bench_streamer
+
+_ cargo build --all --verbose --features="$FEATURES"
 _ cargo test --verbose --lib -- --nocapture --test-threads=1
 
 # Run integration tests serially