Refactor shelling out in Python

[deivid-rodriguez]

There's a lot of duplicated code in the Python ecosystem that deals with shelling out to package managers. This PR refactors it to always use the same helper.

This fixes most of #6110.

[deivid-rodriguez]

This is a slight change where we will now raise stderr concatenated with stdout as the exception message, while before we'd only raise stdout.

dependabot-core/common/lib/dependabot/shared_helpers.rb

Lines 344 to 347 in 1b3368e

	raise SharedHelpers::HelperSubprocessFailed.new(
	message: stderr_to_stdout ? stdout : "#{stderr}\n#{stdout}",
	error_context: error_context
	)

It seems like a good change to me.

[deivid-rodriguez]

Same as the other comment, but reversed. This used to raise an error including only stderr, now we'll raise an error including stdout and stderr concatenated.

Seems fine too I guess!

[deivid-rodriguez]

Same as the other comment in the other run_poetry_command method.

[yeikel]

It's always great to see these cleanups and more so when the tests are happy 🥇

[Nishnha]

This LGTM. I would maybe get another approval from the team though since I haven't used time_taken in my debugging, but maybe someone else has found it useful and doesn't want it removed?

[deivid-rodriguez]

@Nishnha Note that this is not removing time_taken, the same code is present in the common run_shell_command helper which is now used consistently:

dependabot-core/common/lib/dependabot/shared_helpers.rb

Lines 317 to 348 in 1b3368e

	def self.run_shell_command(command,
	allow_unsafe_shell_command: false,
	env: {},
	fingerprint: nil,
	stderr_to_stdout: true)
	start = Time.now
	cmd = allow_unsafe_shell_command ? command : escape_command(command)
	if stderr_to_stdout
	stdout, process = Open3.capture2e(env || {}, cmd)
	else
	stdout, stderr, process = Open3.capture3(env || {}, cmd)
	end
	time_taken = Time.now - start
	# Raise an error with the output from the shell session if the
	# command returns a non-zero status
	return stdout if process.success?
	error_context = {
	command: cmd,
	fingerprint: fingerprint,
	time_taken: time_taken,
	process_exit_value: process.to_s
	}
	raise SharedHelpers::HelperSubprocessFailed.new(
	message: stderr_to_stdout ? stdout : "#{stderr}\n#{stdout}",
	error_context: error_context
	)
	end

Only changes in behavior should be the ones I noticed as inline comments in the PR.