Treat dense text blobs as binary for git grep

[dbeatty10]

resolves #6294

Description

Without this PR, try the following:

git grep "unrendered_config" tests

Not fun!

Then try again with this PR.

Much better:

$ git grep "unrendered_config" tests                 
Binary file tests/functional/artifacts/data/state/v1/manifest.json matches
Binary file tests/functional/artifacts/data/state/v2/manifest.json matches
Binary file tests/functional/artifacts/data/state/v3/manifest.json matches
Binary file tests/functional/artifacts/data/state/v4/manifest.json matches
Binary file tests/functional/artifacts/data/state/v5/manifest.json matches
Binary file tests/functional/artifacts/data/state/v6/manifest.json matches
Binary file tests/functional/artifacts/data/state/v7/manifest.json matches
Binary file tests/functional/artifacts/data/state/v8/manifest.json matches
tests/functional/artifacts/expected_manifest.py:                "unrendered_config": unrendered_model_config,
tests/functional/artifacts/expected_manifest.py:                "unrendered_config": unrendered_second_config,
tests/functional/artifacts/expected_manifest.py:                "unrendered_config": unrendered_seed_config,
...

Checklist

• I have read the contributing guide and understand what's expected of me
• I have signed the CLA
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• I have opened an issue to add/update docs, or docs changes are not required/relevant for this PR
• I have run changie new to create a changelog entry

[ChenyuLInx]

LGTM!!