Feature Request: add support for initialize-target-sequences in MoveTables SwitchTraffic --tablet-types PRIMARY --dry-run mode

[mcrauwel]

Feature Description

We have support to initialize the target sequences during the swtiching of PRIMARY (write) traffic. But in dry run mode these commands seem not to be executed.

2 reasons why I believe this would be useful:

1. I've run into a situation where the initialize-target-sequences took longer than the allowed time (default 15sec) and the SwitchTraffic failed because of this. This wasn't caught in dry-run mode.
2. While dry-run would execute all the steps to check the sequences verify the work it would need to do to figure out if updates are needed (just not the actual updating), we could use the dry-run output as some sort of a fail-safe mechanism in specific use-cases where initialize-target-sequences might not be 100% safe to execute (think busy systems with multi-tenant migrations running)

Use Case(s)

see description