Add copier test, upgrade testcontainers

[meiji163]

Description

This PR adds tests for the copier part of the Migrator. Also upgrade testcontainers to v0.37.0 per #1457 (comment).
The tests are added in migrator_test.go, the rest of the changes are tidying tests and vendoring.

The PR is low risk because the changes only affect tests.

In case this PR introduced Go code changes:

• contributed code is using same conventions as original code
• script/cibuild returns with no formatting errors, build errors or unit test errors.

[Copilot]

Pull Request Overview

This PR adds a new copier integration test for the Migrator component, standardizes and refactors existing tests to use shared test utilities, and upgrades Testcontainers (and other dependencies) to v0.37.0.

• Introduce getTest* helpers and newTestMigrationContext in test_utils.go
• Refactor streamer, migrator, and applier tests to use the MySQL module and shared helpers
• Add TestCopierIntPK to validate the copier logic and bump testcontainers-go to v0.37.0

Reviewed Changes

Copilot reviewed 5 out of 473 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
go/logic/test_utils.go	Add constants and helper functions for DB/table names and connection contexts
go/logic/streamer_test.go	Refactor to use mysql.Run, shared utils, and table helpers
go/logic/migrator_test.go	Rename tests, inject newTestMigrationContext, add TestCopierIntPK
go/logic/applier_test.go	Refactor to use shared utils for container setup and teardown
go.mod	Upgrade github.com/testcontainers/testcontainers-go and related modules to v0.37.0

Comments suppressed due to low confidence (2)

go/logic/migrator_test.go:435

• The database name in the SHOW TABLES query is still hardcoded to test. Use testMysqlDatabase instead of the literal test to stay consistent with the helper constants.

		default:

go/logic/migrator_test.go:397

• Using range directly on an int64 (numRows) is invalid in Go and will not compile. Change to an indexed loop, e.g. for i := int64(0); i < numRows; i++ {}.

	for i := range numRows {