The installer script should disable OTEL SDK

[ThorstenHans]

The Installer Script (install.sh) does not deactivate the OpenTelemetry SDK. The SDK being enabled leads to installation errors when using the script on system like GitHub Actions.

The SDK should be disabled before spin is invoked (e.g. to install plugins or templates) and re-activated once all spin invocations are done.

[itowlson]

Could you say more about the error that you're seeing? If installing plugins and templates fails in the presence of the OTel SDK, that's a breaking change and we need to fix it in Spin, not just in this particular install script.