Delete leftover build script

[jeffwidman]

This script is a leftover from when we had a monolithic image for all ecosystems.

Now that we use a specific docker image just for python, that dockerfile uses the parameterized version of this script, called build_for_version.

You can see more historical context in this commit: 3e99935

I grep'd around and couldn't find any remaining usages of the build script, so let's nuke it.

[deivid-rodriguez]

If you change a dependency and then manually run the build script, will you want all native helpers reinstalled for tests to pass? I guess that's why the previous build script installed for all pythons?

[jeffwidman]

I guess that's why the previous build script installed for all pythons?

I don't think so... this commit explains that the build script was left-in for the monolithic image... probably it was not removed when the multi-stage build was added in order to reduce risk during initial rollout, and only later once everything was proven stable was it removed but removing this script was overlooked.

If you change a dependency and then manually run the build script, will you want all native helpers reinstalled for tests to pass?

Technically that's true and this would be a convenience, but TBH it's a pain to have to keep the list of python versions updated here... Historically the frequency that we need to re-run the build script for testing seems like it's smaller than the frequency of bumping python releases.

It also feels dangerous to have a build script that someone might use during dev flow that's different than the build-for-helpers script that is actually used in prod.