release-22.1: docker: fix docker image to suit storage in memory

[blathers-crl]

Backport 2/2 commits from #80036 on behalf of @ZhouXing19.

/cc @cockroachdb/release

---

Currently the datasets created in the init process are stored on disk,
and they are inaccessible if the “real” server is started with storage in memory.

This is because, for the container initialization, the current logic is:

1. start_init_server: start the single-node server in the background, with
   default on-disk storage setting;
2. run_init_queries: create default db and user, and run the init scripts
   saved in
   docker-entrypoint-initdb.d;
3. stop the init server and restart the server with given parameters in foreground.

In this commit we start and keep running the init server with the given
parameters, and eliminate the “stop and restart” step. Also, bring the server
process from background to foreground with fg once all init queries are finished.

Fixes #80005.

Release note (docker): refactor the initialization process of the docker image
to accomodate initialization scripts with memory storage.

---

Release justification: (Bug fixes and low-risk updates to new functionality) fix the docker image for the memory storage use case

[blathers-crl]

Thanks for opening a backport.

Please check the backport criteria before merging:

• Patches should only be created for serious issues or test-only changes.
• Patches should not break backwards-compatibility.
• Patches should change as little code as possible.
• Patches should not change on-disk formats or node communication protocols.
• Patches should not add new functionality.
• Patches must not add, edit, or otherwise modify cluster versions; or add version gates.

If some of the basic criteria cannot be satisfied, ensure that the exceptional criteria are satisfied within.

• There is a high priority need for the functionality that cannot wait until the next release and is difficult to address in another way.
• The new functionality is additive-only and only runs for clusters which have specifically “opted in” to it (e.g. by a cluster setting).
• New code is protected by a conditional check that is trivial to verify and ensures that it only runs for opt-in clusters.
• The PM and TL on the team that owns the changed code have signed off that the change obeys the above rules.

Add a brief release justification to the body of your PR to justify this backport.

Some other things to consider:

• What did we do to ensure that a user that doesn’t know & care about this backport, has no idea that it happened?
• Will this work in a cluster of mixed patch versions? Did we test that?
• If a user upgrades a patch version, uses this feature, and then downgrades, what happens?

[cockroach-teamcity]

This change is 

[janpio]

(Subscribing so I get a notification when this goes out - hopefully)

[otan]

@ZhouXing19 @rafiss should we merge this to v22.1.0?

[rafiss]

I'm in favor of adding it to 22.1.0. let me see what's needed