Refactor: foreign key in semantic analysis phase

[harshit-gangal]

Description

This PR moves some foreign keys related to DML analysis to the semantic analysis phase. This helped simplify the logic for retrieving foreign keys that require VTGate to manage them.

Related Issue(s)

• RFC: Foreign Key Support in Vitess #12967

Checklist

• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on the CI

Deployment Notes

[vitess-bot]

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[GuptaManan100]

Looks good to me and Harshit!