chore: undo bitgo version change and remove lowdb

package.json

@@ -14,7 +14,7 @@
     "bignumber.js": "9.0.1",
     "bip39": "^2.3.1",
     "bitcoind-rpc": "^0.7.0",
-    "bitgo": "4.47.0",
+    "bitgo": "11.15.0",
     "ccxt": "1.51.36",
     "compression": "^1.7.4",
     "connect-pg-simple": "^6.2.1",
@@ -43,7 +43,6 @@
     "libphonenumber-js": "^1.7.38",
     "lnd-async": "^1.8.0",
     "lodash": "^4.17.10",
-    "lowdb": "^1.0.0",
     "mailgun-js": "^0.21.0",
     "make-dir": "^1.0.0",
     "mem": "^1.1.0",