LIB-982: Implement versioning workflows and clean up GitHub Actions in operator fork

[KevinKlaesRackspace2]

Description

Implements label-driven semver versioning for the percona-server-mongodb-operator fork, mirroring the pattern established in liberty-temporal-platform. This replaces manual version bumps with automated, PR-label-gated version management and removes irrelevant upstream Percona workflows.

What this does

New workflows:

• auto-version-bump.yaml — On PR events with bump:patch/minor/major labels, automatically bumps pkg/version/version.txt and commits to the PR branch. Includes merge-conflict auto-resolution for the version file and skip logic when the version is already ahead of base.
• label-check.yaml — Required status check that blocks merge on PRs with code changes unless a version label or skip-release is present.

Removed upstream cruft:

• scan.yml (pushes to Percona's Docker Hub — not ours), stale.yml and labeler.yml (community PR management — not applicable), renovate.yaml (redundant with existing dependabot.yml), plus their config files (.github/labeler.yml, .github/pr-badge.yml).

Updated:

• reviewdog.yml — Added github.com/objectrocket as company prefix for goimports-reviser; removed release-* branch conditional on the manifests check since we only use main.
• pkg/version/version.txt — Updated from 1.22.0 to 1.22.0-1 to bootstrap the subversion scheme.
• pkg/version/version.go — Added SubVersion() helper that parses the -N suffix from the version string.

Subversion scheme

Since 1.22.0 tracks the upstream Percona release we forked from, we can't meaningfully bump patch/minor/major in the traditional sense for our own changes. Instead, bump:patch increments a -N suffix (1.22.0-1 → 1.22.0-2 → ...). bump:minor and bump:major are reserved for upstream rebases (e.g., moving to 1.23.0-1). Image tags use this directly: 1.22.0-1-objectrocket.

Reviewer notes

• The conflict-resolution step in auto-version-bump.yaml merges base into the PR branch when the only conflict is the version file, then immediately overwrites it with the computed bump. If non-version conflicts exist, it aborts. This matches the liberty-temporal-platform behavior.
• label-check.yaml uses dorny/paths-filter@v4 pinned to v4 (not v3 like some other repos). This is intentional — v4 handles the pull_request event correctly without needing a checkout step.
• The build-operator.yml workflow is unchanged. It already reads pkg/version/version.txt and its workflow_dispatch manual tag override continues to work as a fallback.
• CRD patches and deploy manifests have minor diffs because make generate manifests regenerated them with the updated version string.

CHANGE DESCRIPTION

Problem:
Short explanation of the problem.

Cause:
Short explanation of the root cause of the issue if applicable.

Solution:
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CHECKLIST

Jira

• LIB-982
• Is the Jira ticket created and referenced properly?
• Does the Jira ticket have the proper statuses for documentation (Needs Doc) and QA (Needs QA)?
• Does the Jira ticket link to the proper milestone (Fix Version field)?

Tests

• Is an E2E test/test case added for the new feature/change?
• Are unit tests added where appropriate?
• Are OpenShift compare files changed for E2E tests (compare/*-oc.yml)?

Config/Logging/Testability

• Are all needed new/changed options added to default YAML files?
• Are all needed new/changed options added to the Helm Chart?
• Did we add proper logging messages for operator actions?
• Did we ensure compatibility with the previous version or cluster upgrade process?
• Does the change support oldest and newest supported MongoDB version?
• Does the change support oldest and newest supported Kubernetes version?