Fix race condition for Docker local tests

[achantavy]

Summary

Describe your changes.

Before:

1. Pull down a fresh cartography from github
   

2. Build the container with docker build -t cartography-cncf/cartography-dev -f dev.Dockerfile ./ (I forgot to screenshot this step)

3. Running the docker-compose linter works on the first try because the initialization step takes a while:
   

4. [Failure] But subsequent linter runs fail with "is this a git repository?"
   

After:

1. Pull down fresh cartography from github and checkout this fix branch (fixdcwait)
   

2. Build container
   

3. Run linter on the first try
   

4. [SUCCESS] Subsequent linter runs work because we've added a waiting mechanism
   

Related issues or links

Include links to relevant issues or other pages.

• https://github.com/lyft/cartography/issues/...

Checklist

Provide proof that this works (this makes reviews move faster). Please perform one or more of the following:

• Update/add unit or integration tests.
• Include a screenshot showing what the graph looked like before and after your changes.
• Include console log trace showing what happened before and after your changes.