add `stress-ng` and `gremlin` to apps_groups.conf (#12165)

collectors/apps.plugin/apps_groups.conf

@@ -339,3 +339,10 @@ filecoin: lotus* lotus-miner* lotus-worker*
 solana: solana*
 web3: *hardhat* *ganache* *truffle* *brownie* *waffle*
 terra: terra* mantle*
+
+# -----------------------------------------------------------------------------
+# chaos engineering tools
+
+stress: stress stress-ng*
+gremlin: gremlin*
+