registry repository list-v2 ignores --format and --no-header flags

**Describe the Issue:**

The `--format` and `--no-header` flags are completely ignored by `doctl registry repository list-v2`. The command outputs all columns with headers regardless of the format specified.

**Steps to reproduce:**

```bash
# Expected: Only repository names, no header
doctl registry repository list-v2 --format Name --no-header

# Actual output: Full table with all columns and header
Name Latest Manifest Latest Tag Tag Count Manifest Count Updated At
my-app-prod sha256:a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2 latest 2 3 2025-12-04 06:57:34 +0000 UTC
my-app-stg sha256:f6e5d4c3b2a1f6e5d4c3b2a1f6e5d4c3b2a1f6e5d4c3b2a1f6e5d4c3b2a1f6e5 latest 3 5 2025-12-11 18:35:05 +0000 UTC
```

**Expected behavior:**

```bash
doctl registry repository list-v2 --format Name --no-header
# Should output:
my-app-prod
my-app-stg
...
```

**Workaround:**

Using `--output json` with `jq` works correctly:
```bash
doctl registry repository list-v2 --output json | jq -r '.[].name'
```

**Environment:**
- doctl version: 1.148.0 (also reproduced on 1.141.0 in CI)
- OS: Ubuntu 22.04 / Ubuntu 24.04 (GitHub Actions)
- Installation method: GitHub Actions `digitalocean/action-doctl@v2`

**Additional Details:**

The same issue affects `doctl registry repository list` (non-v2). This breaks scripts that rely on `grep -Fxq` for exact matching since the full row is returned instead of just the name.

Additional Note: We noticed this issue started to happen since December 27th