Langchain destination: Clean up spec schema

[flash1293]

This PR removes the discriminator property from the pydantic-generated json schema. The discriminator property is not used by the platform and references non-existing definitions as they are inlined into the places they are used (this happens to ensure compatibility with the UI)

[github-actions]

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[girarda]

TIL about pydantic discreminators.

[girarda]

change looks good. leaving a note that this is something we could do at the CDK level if this is a widespread issue

[github-actions]

destination-langchain test report (commit b59979f4e3) - ❌

⏲️ Total pipeline duration: 04mn38s

Step	Result
Validate airbyte-integrations/connectors/destination-langchain/metadata.yaml	✅
Connector version semver check	✅
Connector version increment check	✅
QA checks	✅
Code format checks	❌
Connector package install	✅
Build destination-langchain docker image for platform linux/x86_64	✅
Unit tests	✅
Integration tests	✅

🔗 View the logs here

☁️ View runs for commit in Dagger Cloud

Please note that tests are only run on PR ready for review. Please set your PR to draft mode to not flood the CI engine and upstream service on following commits.
You can run the same pipeline locally on this branch with the airbyte-ci tool with the following command

airbyte-ci connectors --name=destination-langchain test

[github-actions]

destination-langchain test report (commit b59979f4e3) - ❌

⏲️ Total pipeline duration: 04mn16s

Step	Result
Validate airbyte-integrations/connectors/destination-langchain/metadata.yaml	✅
Connector version semver check	✅
Connector version increment check	✅
QA checks	✅
Code format checks	❌
Connector package install	✅
Build destination-langchain docker image for platform linux/x86_64	✅
Unit tests	✅
Integration tests	✅

🔗 View the logs here

☁️ View runs for commit in Dagger Cloud

Please note that tests are only run on PR ready for review. Please set your PR to draft mode to not flood the CI engine and upstream service on following commits.
You can run the same pipeline locally on this branch with the airbyte-ci tool with the following command

airbyte-ci connectors --name=destination-langchain test

[github-actions]

destination-langchain test report (commit 89e21aef61) - ✅

⏲️ Total pipeline duration: 02mn45s

Step	Result
Validate airbyte-integrations/connectors/destination-langchain/metadata.yaml	✅
Connector version semver check	✅
Connector version increment check	✅
QA checks	✅
Code format checks	✅
Connector package install	✅
Build destination-langchain docker image for platform linux/x86_64	✅
Unit tests	✅
Integration tests	✅

🔗 View the logs here

☁️ View runs for commit in Dagger Cloud

Please note that tests are only run on PR ready for review. Please set your PR to draft mode to not flood the CI engine and upstream service on following commits.
You can run the same pipeline locally on this branch with the airbyte-ci tool with the following command

airbyte-ci connectors --name=destination-langchain test