Allow OBS project retrieval for manual `krel obs stage/release`

[saschagrunert]

This code path requires a --project to be set manually:

release/pkg/obs/obs.go

Lines 223 to 227 in e229265

	} else if foundManualOption {
	if o.Project == "" {
	return errors.New("project is required")
	}
	}

It would be great if we can re-use the existing project generation in

release/pkg/obs/stage.go

Lines 321 to 347 in e229265

	// GenerateOBSProject generates the OBS project name for the release.
	// Uses the project from the options if set, otherwise generates the project
	// name based on the release type.
	func (d *DefaultStage) GenerateOBSProject() error {
	if d.options.Project != "" {
	logrus.Infof("Using provided OBS project: %s", d.options.Project)
	d.state.obsProject = d.options.Project
	return nil
	}
	primeSemver, err := util.TagStringToSemver(d.state.versions.Prime())
	if err != nil {
	return fmt.Errorf("parsing prime version as semver: %w", err)
	}
	namespace := OBSNamespacePrerelease
	if d.options.ReleaseType == release.ReleaseTypeOfficial {
	namespace = OBSNamespaceStable
	}
	d.state.obsProject = fmt.Sprintf("%s:core:%s:v%d.%d:build", OBSKubernetesProject, namespace, primeSemver.Major, primeSemver.Minor)
	logrus.Infof("Using OBS project: %s", d.state.obsProject)
	return nil
	}

(and the duplicate in release.go)

to be able to just run

> krel obs stage --packages cri-tools --version 1.28.0 --stream --nomock

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/lifecycle stale

[xmudrii]

/remove-lifecycle stale

[k8s-triage-robot]

The Kubernetes project currently lacks enough contributors to adequately respond to all issues.

This bot triages un-triaged issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
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/lifecycle stale

[xmudrii]

/remove-lifecycle stale

[k8s-triage-robot]

The Kubernetes project currently lacks enough contributors to adequately respond to all issues.

This bot triages un-triaged issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Mark this issue as fresh with /remove-lifecycle stale
• Close this issue with /close
• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/lifecycle stale