Code duplication (DRY violations) in reusable workflows

## Description
Both global-ci.yml and global-ci-bundle.yml contain significant code duplication between API and UI test jobs, with TODO comments noting this issue.

## Locations
- .github/workflows/global-ci.yml
- .github/workflows/global-ci-bundle.yml

## Details

### TODO comments acknowledging the issue:
- global-ci-bundle.yml:298 - "TODO Should DRY this"
- global-ci-bundle.yml:424 - "TODO Should DRY this"
- global-ci.yml:197 - "TODO Should DRY this"
- global-ci.yml:341 - "TODO Should DRY this"

### Duplicated code blocks:
Both API and UI test jobs repeat the following setup steps:

1. **Docker buildx setup**
```yaml
- name: set up docker buildx
uses: docker/setup-buildx-action@v2
```

2. **Minikube start** (with version-specific conditionals in global-ci.yml)
```yaml
- name: start minikube
uses: konveyor/tackle2-operator/.github/actions/start-minikube@...
```

3. **Artifact download**
```yaml
- name: Download artifact
uses: actions/download-artifact@v4
```

4. **Image loading**
```yaml
- name: Load images
run: |
eval $(minikube -p minikube docker-env)
for image in $(find "${IMAGES_PATH}" -type f -name "*.tar"); do
docker load --input ${image}
done
```

5. **Bundle creation/installation** (in global-ci-bundle.yml)
```yaml
- name: Make bundle
- name: Push bundle
- name: Install konveyor
```

6. **Konveyor installation** (in global-ci.yml with version conditionals)
```yaml
- name: install konveyor (multiple conditional steps)
```

## Impact
- **Maintenance burden**: Changes must be made in multiple places (2 jobs × 2 workflows = 4 locations)
- **Drift risk**: Jobs can drift apart if updates aren't applied consistently
- **Harder reviews**: More code to review and understand
- **Longer workflows**: Duplicated YAML increases file size
- **Already drifting**: Issue #139 shows API/UI jobs already have different configurations (java-provider-image)

## Recommendation

### Option 1: Create composite action (preferred)
Extract common setup into `.github/actions/setup-test-environment/action.yml`:
- Docker buildx setup
- Minikube start
- Artifact download and loading
- Konveyor installation

### Option 2: Use job-level reusable workflow
Create `.github/workflows/setup-konveyor.yml` that both test jobs can call.

### Option 3: Use YAML anchors (limited in GitHub Actions)
GitHub Actions has limited support, but could work for some shared config.

### Example composite action structure:
```yaml
name: Setup Konveyor Test Environment
inputs:
operator_tag:
description: Operator version
required: true
component_name:
description: Component to test
required: false
# ... other inputs
runs:
using: composite
steps:
- name: set up docker buildx
# ...
- name: start minikube
# ...
# etc.
```

Then both jobs would just use:
```yaml
- name: Setup test environment
uses: ./.github/actions/setup-test-environment
with:
operator_tag: ${{ inputs.operator_tag }}
# ... other inputs
```

## Benefits of fixing:
- Single source of truth for setup logic
- Consistent behavior between API and UI tests
- Easier maintenance and updates
- Reduced chance of configuration drift
- Shorter, more readable workflow files

## Related Files
- .github/workflows/global-ci.yml:197-275 (API test setup)
- .github/workflows/global-ci.yml:341-422 (UI test setup)
- .github/workflows/global-ci-bundle.yml:298-355 (API test setup)
- .github/workflows/global-ci-bundle.yml:424-481 (UI test setup)

Start by comparing the API and UI test setup sections in .github/workflows/global-ci.yml:197-275 and :341-422, then review the corresponding sections in global-ci-bundle.yml:298-355 and :424-481. Use the TODO comments as entry points and identify the shared setup boundary and required inputs. Done means the duplicated setup is consolidated while both workflows retain their existing version conditionals and test behavior.

Written by the indexing model from the issue text.