remove bigint migration flags, add placement strategy flags

[vito]

Why do we need this PR?

syncs values.yml + templates to latest flags on Concourse master

Changes proposed in this pull request

• remove bigint migration flags
• add flags for placement strategy changes

Contributor Checklist

• [ ] ~Variables are documented in the README.md~
  • i would like to peacefully protest this as it doesn't even include the properties we changed and should really just be generated by a script or something
• [ ] Which branch are you merging into?
  • master is for changes related to the current release of the concourse/concourse:latest image and should be good to publish immediately
  • dev is for changes related to the next release of Concourse (aka unpublished code on master in concourse/concourse)

Reviewer Checklist

This section is intended for the core maintainers only, to track review progress. Please do not fill out this section.

• [ ] Code reviewed
• [ ] Topgun tests run
• [ ] Back-port if needed
• [ ] Is the correct branch targeted? (master or dev)