Logical replication test - high WAL generation rate and replication lag.

Perform a logical replication test with a high WAL generation rate to find out at what number of WALs per second the replication lag begins to accumulate.

PostgreSQL version: 14

AWS Spot instance: i3.4xlarge (2x for Publication and Subscription)

• vCPU: 16
• Memory: 122 GiB
• Disk: 2x 1900 GiB NVMe SSD (ephemeral)
• Network: Up to 10 Gigabit
• OS: Ubuntu 20.04

related issue in GitLab benchmarking environment (PG 12): https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/15522