patch(build_charms_with_cache.yaml): Remove local: from charm file …

…path (#54)

python-libjuju (called in `ops_test.model.deploy()`) will automatically
add the `local:` prefix if it is not present and the path begins with
`.`

https://github.com/juju/python-libjuju/blob/c7d0a1049125e41c70987896b0ffd3463675ca75/juju/model.py#L1713-L1714

Makes it easier to override ops_test.build_charm in a way that's
compatible with the original method

collect_charms.py

@@ -44,7 +44,7 @@ def get_base_versions(path_to_charmcraft_yaml: Path) -> list[str]:
                 "_job_display_name": f"Build {charm_name} charm | {version}",
                 "bases_index": index,
                 "directory_path": path.as_posix(),
-                "file_path": f"local:./{path/charm_name}_ubuntu-{version}-amd64.charm",
+                "file_path": f"./{path/charm_name}_ubuntu-{version}-amd64.charm",
             }
         )
 logging.info(f"Collected {charms=}")