[ENT] drop discovered_license from required index on certifyLegal

[pxp928]

Description of the PR

drop discovered_license from required index as it is covered by the discovered_license_hash Migration also created!

fixes https://github.com/guacsec/guac/issues/2138

PR Checklist

• [ ] All commits have a Developer Certificate of Origin (DCO) -- they are generated using -s flag to git commit.
• [ ] All new changes are covered by tests
• [ ] If GraphQL schema is changed, make generate has been run
• [ ] If GraphQL schema is changed, GraphQL client updates/additions have been made
• [ ] If OpenAPI spec is changed, make generate has been run
• [ ] If ent schema is changed, make generate has been run
• [ ] If collectsub protobuf has been changed, make proto has been run
• [ ] All CI checks are passing (tests and formatting)
• [ ] All dependent PRs have already been merged