[EC-497] Fix memory leaks in tests (#3421)

* Add isolatedModules:true

* Add manual typechecking in CI for libs/ tests

jest.config.js

@@ -26,4 +26,13 @@ module.exports = {
   // https://github.com/facebook/jest/issues/9430#issuecomment-1149882002
   // Also anecdotally improves performance when run locally
   maxWorkers: 3,
+  globals: {
+    "ts-jest": {
+      // Further workaround for memory leak, recommended here:
+      // https://github.com/kulshekhar/ts-jest/issues/1967#issuecomment-697494014
+      // Makes tests run faster and reduces size/rate of leak, but loses typechecking on test code
+      // See https://bitwarden.atlassian.net/browse/EC-497 for more info
+      isolatedModules: true,
+    },
+  },
 };