Optimize Multiplatform cache builds

[potiuk]

This PR starts an ARM EC2 instance and forwards socket via SSH
so that it can be used by docker buildx build with airflow_cache
multi-platform builders. Then it appends it to the regular
builder making the builds run up to 10 minutes rather than
1.5 hours.

The instance is created only when "main" build reaches the cache
build job/step.

The instances run for maximum 50 minutes and then self-terminate just
in case, also the instance is killed immediately when the job finishes
(no matter if succesfully or not).

Part of #15635

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[potiuk]

This is an optimization (10x speedup) of building our mutliplatform images on CI as cache for other builds. I run it manually on my Macbook so far because of the time it took to build with emulation, but with this one the maximum total time of building the multiplatform images (both CI and PROD) on our CI is down to ~25 minutes from > 3 hours.

Completed, succesful run (I limited it and removed the regular tests there) can be found here: https://github.com/apache/airflow/runs/5626562720?check_suite_focus=true

With this approach we can actually even start thinking about running selected tests on ARM in "main" without actually spinning an ARM runner - that would be a nice step to follow but it is not implemented yet). Github Actions are also close to supporting ARM public runners it seems, so we can eventually get it running for both self-hosted and public runners.

I added several protections against spinnig up too many instances (including self-termination after 50 minutes) , but I will keep watching if we are not running too many of those once we merge it.

[potiuk]

Hey @ashb -> would love to merge this one as currently main is failing as I had to disable qemu support for our runners (to make sure that ARM engine will be used to build the images).

[potiuk]

Anyone ? Cache refresh should be enabled soon.

[potiuk]

:D ?

[potiuk]

When we merge the two - this one and #22492 .... It will make our caching finally complete for CI and mutli-platform dev builds :)

[github-actions]

The PR most likely needs to run full matrix of tests because it modifies parts of the core of Airflow. However, committers might decide to merge it quickly and take the risk. If they don't merge it quickly - please rebase it to the latest main at your convenience, or amend the last commit of the PR, and push it with --force-with-lease.