Remove conda tests from validation framework

Remove from conda tests from validation framework. Validation Framework Wiki: https://github.com/pytorch/test-infra/wiki/Validation-Framework Code: https://github.com/pytorch/builder/blob/main/.github/workflows/validate-*.yml and scripts: https://github.com/pytorch/builder/blob/main/.github/scripts/validate_* When MATRIX_PACKAGE_TYPE == conda - skip, or no-op. At this point no modifications to https://github.com/pytorch/test-infra/blob/main/.github/workflows/generate_binary_build_matrix.yml are needed since these will be removed later when deprecating conda builds. Please note for pipy test we can still use conda env if needed, since we create conda env and run all tests for all platforms within this env: https://github.com/pytorch/builder/blob/main/.github/scripts/validate_binaries.sh#L23