Fix openapi-generation isolation problem among plugins

[pedro-psb]

The publishing workflow is failing due to dependency issues with existing plugins when generating their openapi specs (uses uv as subprocess to call pulpcore-manager openapi command).

Each openapi spec generation call to a specific plugin would install all available plugins. Each generation should be isolated and not interfere with one another.

Sample error:

Error message:
Because only pulp-rpm==3.39.0.dev0 is available and
      pulp-rpm==3.39.0.dev0 depends on pulpcore>=3.111.0,<3.115,
      we can conclude that all versions of pulp-rpm depend on
      pulpcore>=3.111.0,<3.115.
      And because only the following versions of pulpcore are available:
          pulpcore<3.111.0
          pulpcore>=3.115
      and you require pulp-rpm, we can conclude that your requirements are
      unsatisfiable.

Aborted with a BuildError!
make: *** [Makefile:61: docs-prod] Error 1