Build: Update plugin installation in custom Dockerfile

[hoptical]

What is this feature?

There is a for loop in the plugin installation layer in the custom Dockerfile. The problem is that if the installation of any plugin except the last one faces an error (e.g., Network error and etc.), the layer will continue to run and the image is built successfully, and the user may not be aware of the missing plugins in the image.

This PR adds the set -e command to the layer to exit the layer with a non-zero code in case of any failure in the loop and prevent the image from building successfully.

Why do we need this feature?

Users should be certain about the successful installation of all plugins, especially for the CI/CD pipelines.

Who is this feature for?

Anyone who uses the custom Dockerfile for pre-installed plugins.

Special notes for your reviewer:

Please check that:

• It works as expected from a user's perspective.
• If this is a pre-GA feature, it is behind a feature toggle.
• The docs are updated, and if this is a notable improvement, it's added to our What's New doc.

[DanCech]

I think this is a sensible approach, and agree that failing to build is a better approach than producing an image that is missing a specified plugin.