[release-16.0] MoveTables: add flag to specify that routing rules should not be created when a movetables workflow is created

[rohit-nayak-ps]

Description

This PR adds a new flag --no-routing-rules to MoveTables in v16. Usually when a MoveTables workflow is created we create routing rules pointing the participating tables to the source keyspace and then reroute them to the target keyspace after traffic is switched.

However for some use cases, like specified in #13851, we do not want these routing rules to be created. The expected flow for workflows using this routing rule is:

• taking the app offline
• waiting manually for the workflow to catchup with the source
• cancel the workflow with --keep-data
• update the app config to point to the target
• bring the app back online

Note
Adding this for v16 since the immediate requirement is for that version. Once it is confirmed that this approach works for this use-case, I will forward port it.

Related Issue(s)

• Feature Request: Add option to MoveTables to be created without RoutingRules #13851 (this is the v16 implementation, v17/main to follow)

Docs: vitessio/website#1568

Checklist

• "Backport to:" labels have been added if this change should be back-ported
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on the CI
• Documentation was added or is not required

[vitess-bot]

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[mattlord]

We need to add this flag to vtctldclient as well.