docs: update articles for production build change

[tltv]

Removed production profile from articles that use example apps that build or will build production package without any production profile.

Part of vaadin/flow#22464

WIP: starters are not updated yet and they are pending on new Spring Boot 4 release that enables removal of the production profile.

[github-actions]

AI Language Review

Build a Project

1. In the section "Make a Production Build," the change from "activating the production profile" to "activating the package goal" might be misleading since it's about the goals provided by Maven, which don't require activation like profiles do. Clarify that you simply run the package (not a "goal activation").

2. The sentence "The package goal not only builds the frontend, but also excludes the development server bundle since it contains features that aren't used in production" can be improved for clarity. Consider mentioning that the exclusion of the development server bundle is part of optimization for production by the Vaadin plugin.

3. Under "A Peek Under the Hood," revise "the --secret option works because the provided Dockerfile in the walking skeleton mounts the files, parses them and passes them on to Maven," to maintain a clear sequence of operations. It should clarify that the Dockerfile uses secrets, then explain how they're passed or utilized by Maven.

For readability and logical flow, include additional context or instruction when switching between examples particularly regarding changes to the Maven plugin usage from profiles to goals.