DON'T DEPLOY: Default enable code suggestions on all current namespaces

Update 2023-04-19 16:30

Please see #408104. We do not want to deploy or run this migration

What does this MR do and why?

• Changes all existing namespace_settings.code_suggestions values to true as per #407766 (closed)
• !117895 (merged) will handle all new namespaces setting this as default and should be merged first
• effects ~17,800,000 namespace_settings

Database

• Entire migration takes ~25mins on database lab without batching - https://console.postgres.ai/gitlab/gitlab-production-tunnel-pg12/sessions/17830/commands/59499 (warm 2nd run)
• Each batch takes on database lab(~230ms w/in 1s background migration guideline) - https://console.postgres.ai/gitlab/gitlab-production-tunnel-pg12/sessions/17830/commands/59505

Screenshot

📓 taken before changing batch size from 1,000 to 10,000

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #407766 (closed)