🏗 Use Docker containers in CircleCI builds, and other optimizations

[danielrozenberg]

This PR makes several optimizations to CircleCI builds that shave a "large PR" (i.e., one with the RUNTIME build target) from ~20 to ~16 minutes. Together with upcoming optimizations to Bundle Size, Unit Tests, and End-to-End Tests we estimate this can go down to ~12 minutes eventually

This PR:

• Replaces VM executors with Docker containers, which spin up immediately (resolving the common complaint of "my PR is stuck on spinning up the environment for the past 20 minutes)
• Reuses CircleCI's built-in npm dependencies management steps, which are more efficient than simply calling npm ci
• Removes a dangling TODO from .sh files
• Splits Validator Tests to its own executor using a JRE-enabled Docker container (the Node container does not contain the JRE)
• Organizes steps in the .circleci/config.yml file
• Removes the 10 seconds delay for version checks in the amp command when running in a CI environment
• Disabled 13 e2e tests that became (even more) flaky (See Fix e2e tests that became flaky on CircleCI with the move to Docker containers #35241)

[rsimha]

Looping in @kristoferbaxter who requested that this be discussed during design review before we actually check in the change.

@danielrozenberg Would it be possible to write up an I2I for the move to docker containers and run it by wg-approvers to make sure there are no new considerations to think of? And if this meets the bar for a design review, can we use an upcoming time slot?

[danielrozenberg]

@danielrozenberg Would it be possible to write up an I2I for the move to docker containers and run it by wg-approvers to make sure there are no new considerations to think of? And if this meets the bar for a design review, can we use an upcoming time slot?

An I2I is a bit of an overkill - switching how we run our CI tasks is an implementation detail, there's no feature changes here. The discussion on flakes is here above and I think that's the only thing that seriously needs discussing :)

[alanorozco]

Approved skipping tests.