CircleCI runs integration tests against dev servers, not production builds

[snario]

This is generally bad practice and if we can use the production builds as targets for our integration tests we could avoid some weird prod-only bugs. Here is a starter diff:

diff --git i/.circleci/config.yml w/.circleci/config.yml
index b79ce6402..92654d53b 100644
--- i/.circleci/config.yml
+++ w/.circleci/config.yml
@@ -463,12 +463,15 @@ workflows:
       - integration-test-rps:
           requires:
             - prepare
+            - build
       - integration-test-web3torrent:
           requires:
             - prepare
+            - build
       - integration-test-web3torrent-with-hub:
           requires:
             - prepare
+            - build
       - release-pull-request:
           requires:
             - prepare
diff --git i/bin/start-servers.sh w/bin/start-servers.sh
index 3cf9e9b51..6fb1c7c50 100755
--- i/bin/start-servers.sh
+++ w/bin/start-servers.sh
@@ -36,11 +36,11 @@ yarn start:shared-ganache | tee $E2E_ROOT/shared-ganache.log &
 
 yarn run wait-on -t $WAIT_ON_TIMEOUT -i $WAIT_ON_INTERVAL $MONOREPO_ROOT/.ganache-deployments/ganache-deployments-8545.json
 
-cd $PACKAGES/$APP 
-yarn start | tee $E2E_ROOT/$APP.log &
+cd $PACKAGES/$APP/build
+python -m SimpleHTTPServer 3000 | tee $E2E_ROOT/$APP.log &
 
-cd $PACKAGES/xstate-wallet
-yarn start | tee $E2E_ROOT/xstate-wallet.log &
+cd $PACKAGES/xstate-wallet/build
+python -m SimpleHTTPServer 3055 | tee $E2E_ROOT/xstate-wallet.log &
 
 cd $PACKAGES/simple-hub
 yarn hub:start:dev | tee $E2E_ROOT/hub.log &