revert(tmachine): revert package-installed Podman driver suites - #4206

Summary

Revert #4107 to restore the previous Podman qualification setup while CI failures are investigated. The three Fedora Podman driver-specific branch lanes return to the binary installer, and their fixtures return to the prior gateway configuration and service handling.

Related Issue

Reverts #4107 (commit 8990656).

No issue required: explicitly requested, mechanical rollback of test-harness and CI changes.

Changes

• Apply the exact inverse of test(tmachine): support package-installed Podman driver suites #4107 across its 13 files, including its documentation updates.
• Remove the test gateway context role introduced by test(tmachine): support package-installed Podman driver suites #4107.
• Preserve subsequent changes on main.

Testing

• git diff --cached --check passed before commit.
• Compared stable patch IDs: this change exactly matches the inverse of 8990656.
• Checked for remaining references to the removed openshell_test_gateway role; none remain.
• mise run pre-commit and mise run ci: both attempted, but unavailable because mise is not installed in this environment.
• Podman integration/E2E runs: pending CI.

This rollback is not claimed to resolve the Docker E2E failures, which also occurred before #4107 landed.

Checklist

• Follows Conventional Commits.
• Commit is signed off (DCO).
• Test/CI documentation reverted with the implementation; architecture documentation is not applicable.