Fix environment variables not present in Makefile

[RobertLucian]

With this in, if the ./dev/config/env.sh environment file is present, it gets exported for the Makefile's shell, and then it runs the specified target. Otherwise, it proceeds with executing the target regardless.

The - symbol before include tells Makefile to ignore a failure/warning and proceed regardless.

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checklist:

• run make test and make lint
• test manually (i.e. build/push all images, restart operator, and re-deploy APIs)