[25.1] Exclude node_modules at all depths in Docker builds

[mvdbeek]

The pattern node_modules only matches at the root level in .dockerignore (unlike .gitignore). Use **/node_modules to exclude client/node_modules and avoid copying 22GB to the build context.

Taken from @dannon's #21593

How to test the changes?

(Select all options that apply)

• I've included appropriate automated tests.
• This is a refactoring of components with existing test coverage.
• Instructions for manual testing are as follows:
  1. [add testing steps and prerequisites here if you didn't write automated tests covering all your changes]

License

• I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.