[26.0] Store tool shed search index test data in repo

[mvdbeek]

Fixes

ERROR test/unit/tool_shed/test_shed_index.py::test_build_index - requests.exceptions.HTTPError: 429 Client Error: Too Many Requests for url: https://github.com/mvdbeek/toolshed-test-data/blob/master/toolshed_community_files.tgz?raw=true

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.