Synchronous database index removal of `idx_sbom_components_on_name_gin`

What does this MR do and why?

Closes #498913 (closed). Create migration for synchronous index removal

Now that the asynchronous index removal has finished (!167199 (merged)), this migration will remove it synchronously as outlined in the handbook.

References

Please include cross links to any resources that are relevant to this MR. This will give reviewers and future readers helpful context to give an efficient review of the changes introduced.

• https://docs.gitlab.com/ee/development/database/adding_database_indexes.html#add-a-migration-to-destroy-the-index-synchronously
• https://docs.gitlab.com/ee/development/database/adding_database_indexes.html#verify-the-mr-was-deployed-and-the-index-no-longer-exists-in-production
• https://docs.gitlab.com/ee/development/database/database_lab.html#checking-indexes

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Verified that the index no longer exists in production with Database Lab.

How to set up and validate locally

• Pick the migration file from this branch
• Run bin/rails db:migrate
• Verify the structure.sql file has changed as expected