Merge pull request #4549 from mempool/nymkappa/increase-mysql-pool

[database] increase default pool size to 100 connections

backend/src/__fixtures__/mempool-config.template.json

@@ -80,7 +80,8 @@
     "USERNAME": "__DATABASE_USERNAME__",
     "PASSWORD": "__DATABASE_PASSWORD__",
     "PID_DIR": "__DATABASE_PID_FILE__",
-    "TIMEOUT": 3000
+    "TIMEOUT": 3000,
+    "POOL_SIZE": 100
   },
   "SYSLOG": {
     "ENABLED": false,