docker: Speed up startup of the materialized container

[def-]

Local run with bin/mzcompose --find testdrive down && bin/mzcompose --find testdrive run default. Before:

 ✔ Container testdrive-materialized-1          Healthy    61.3s

With this PR

 ✔ Container testdrive-materialized-1          Healthy    10.7s

Another example: bin/mzcompose --find balancerd down && bin/mzcompose --find balancerd run default. Before:

✔ Container balancerd-materialized-1   Healthy  39.6s

After:

✔ Container balancerd-materialized-1   Healthy   5.6s

Checklist

• This PR has adequate test coverage / QA involvement has been duly considered. (trigger-ci for additional test/nightly runs)
• This PR has an associated up-to-date design doc, is a design doc (template), or is sufficiently small to not require a design.
• If this PR evolves an existing $T ⇔ Proto$T mapping (possibly in a backwards-incompatible way), then it is tagged with a T-proto label.
• If this PR will require changes to cloud orchestration or tests, there is a companion cloud PR to account for those changes that is tagged with the release-blocker label (example).
• If this PR includes major user-facing behavior changes, I have pinged the relevant PM to schedule a changelog post.

[Copilot]

Pull Request Overview

This PR optimizes the startup time of the materialized Docker container by implementing a pre-warmed data archive approach and streamlining PostgreSQL initialization. The changes reduce container startup time from 61.3s to 10.7s by creating a pre-built data archive during image build and modifying the runtime initialization to use background processes.

• Creates a pre-warmed data archive during Docker build to avoid cold startup overhead
• Switches from pg_ctlcluster to direct postgres binary execution with background processes
• Consolidates PostgreSQL schema creation into a single command

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
src/materialized/ci/Dockerfile	Adds build-time container warm-up and data archiving
src/materialized/ci/entrypoint.sh	Optimizes runtime startup with background processes and archive extraction
misc/images/materialized-base/Dockerfile	Adds required dependencies and removes redundant PostgreSQL initialization