re-enable file cache integration for VM compute node

[sharnoff]

Problem

#4155 inadvertently switched to a version of the VM builder that leaves the file cache integration disabled by default.

Summary of changes

Re-enable the file vm-informant's file cache integration.

(as a refresher: The vm-informant is the autoscaling component that sits inside the VM and manages postgres / compute_ctl)

See also: neondatabase/autoscaling#265

Checklist before requesting a review

• I have performed a self-review of my code.
• If it is a core feature, I have added thorough tests.
• Do we need to implement analytics? if so did you add the relevant metrics to the dashboard?
• If this PR requires public announcement, mark it with /release-notes label and add several sentences in this section.

Checklist before merging

• Do not forget to reformat commit message to not include the above checklist

[github-actions]

1000 tests run: 960 passed, 0 failed, 40 skipped (full report)

---

Flaky tests (2)

Postgres 15

• test_ondemand_download_timetravel[real_s3]: ✅ release

Postgres 14

• test_close_on_connections_exit: ✅ debug

_{The comment gets automatically updated with the latest test results
da1cf91 at 2023-05-24T18:37:03.364Z :recycle:}