Prefer cflinuxfs4

[acrmp]

Description

• The tile-generator will currently use cflinuxfs3 if it exists even if cflinuxfs4 is the default stack: Pushing applications with cflinuxfs4 cf-platform-eng/tile-generator#325
• Redefine the get_stack function to prefer cflinuxfs4 if available.
• Only use cflinuxfs4 if the go_buildpack is available. Some environments will have the cflinuxfs4 stack but no go_buildpack for cflinuxfs4.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Testing performed?

• Unit tests
• Integration tests
• Acceptance tests

Checklist:

• This PR is being made against the main branch, or relevant version branch
• I have made corresponding changes to the documentation
• I have added testing for my changes

If you have any questions, or want to get attention for a PR or issue please reach out on the #logging-and-metrics channel in the cloudfoundry slack

[Benjamintf1]

Looks kinda hacky, but idk if that's helpful given what seems to be the state of the tile generator.

Have we tried making a pr to tile generator?

Anyways, otherwise lgtm.

[acrmp]

Have we tried making a pr to tile generator?

@Benjamintf1 I created an issue on the tile-generator project (linked in the commit) to consider changing the default.
cf-platform-eng/tile-generator#325