Add option to disable env var interpolation in configs #1168

Job	Run time
Run tests on legacy versions (3.7)	2m 14s
Run tests with different pydantic versions	3m 54s
Run tests with coverage	3m 0s
Run tests (3.8)	2m 8s
Run linters (flake8)	1m 42s
Run tests (3.9)	2m 3s
Run linters (pydocstyle)	1m 45s
Run tests (3.10)	2m 0s
Run linters (mypy)	1m 52s
Run tests (3.11)	2m 7s
Run linters (pylint)	1m 50s
Run tests (3.12)	2m 5s
Run tests (3.13)	2m 6s
	28m 46s

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