run integration tests against DSQL

[danielfrankcom]

Summary

This PR modifies the existing integration tests and surrounding infrastructure to work with Aurora DSQL where they are compatible.

Description

The changes include:

• Added feature flags to select tests which are compatible with DSQL
• Added logic to create/delete DSQL clusters as part of test environment configuration
• Enabled DSQL plugin for tests which are compatible with DSQL to handle authentication
• Added retry mechanism for DDL operations in DataCachePluginTests to avoid issues with DSQL's optimistic concurrency control

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[danielfrankcom]

Please note this change depends on #1477, and the tests will fail until the dependency is merged.

[danielfrankcom]

Integration tests passed in a custom run here, with all the changes integrated. Once the dependency PR has been merged they should pass here too.

[danielfrankcom]

Added an extra commit with fixes from running tests on the integration branch.

[danielfrankcom]

Update to 0a2f489 reworks the integration test changes to separate the DSQL test logic, and avoid changes to other integration tests that don't support IAM.

[danielfrankcom]

2080b29 adds a new integration test which focuses on non-admin user connections.

Change is tested on integration branch here.