Sandbox: revisit need to assign configuration environment from preload script

[bpasero]

We should see if process.env is actually needed once the renderer is fully sandboxed. Currently we overwrite the process.env with properties from the user environment, but not when sandbox is enabled:

vscode/src/bootstrap-window.js

Lines 68 to 70 in 5264ab9

	if (!sandbox) {
	Object.assign(safeProcess.env, configuration.userEnv);
	}

[bpasero]

Checked again, there is no race condition, but we still should support user environment from configuration in sandbox.

[bpasero]

Fixed via 6f3fcd2

@segevfiner fyi this fixes the race condition you found, via:

6f3fcd2#diff-df790e46b6eeafab40b4c8d24b56276f16f314eb4b470ef97192dfafac3105c0R217