🌱 Improve samples linting & fix samples lint issues#3

This commit includes: - Fix linter issues - Refactor fetchCronJob in sample controller reconcile func - Fix getting-started tutorial lint issues - Fix multiversion tutorial lint issues - Fix cronjob-tutorial lint issues - Refactor cronjob controller reconcile to reduce cyclomatic complexity <!-- Hiya! Welcome to Kubebuilder! For a smooth PR process, please ensure that you include the following information: * a description of the change * the motivation for the change * what issue it fixes, if any, in GitHub syntax (e.g. Fixes #XYZ) Both the description and motivation may reference other issues and PRs, but should be mostly understandable without following the links (e.g. when reading the git commit log). Please don't @-mention people in PR or commit messages (do so in an additional comment). please add an icon to the title of this PR depending on the type: - ⚠ (:warning:): breaking - ✨ (:sparkles:): new non-breaking feature - 🐛 (:bug:): bugfix - 📖 (:book:): documentation - 🌱 (:seedling:): infrastructure/other See https://sigs.k8s.io/kubebuilder-release-tools for more information. **PLEASE REMOVE THIS COMMENT BLOCK BEFORE SUBMITTING THE PR** (the bits between the arrows) -->