Update subgraph watcher stacks to configure multiple RPC endpoints (#822)

Run external stack test suite

Success

Set up job7s
Clone project repository8s
Install Python for ARM on Linux0s
Install Python cases other than ARM on Linux22s
Print Python version1s
Install shiv2s
Generate build version file1s
Build local shiv package38s
Run external stack tests3m30s
Notify Vulcanize Slack on CI failure1s
Notify DeepStack Slack on CI failure0s
Complete job5s