Add missing region tags to files used in tutorials

[bourgeoisor]

This PR adds some region tags that were missing from files used in various tutorials. Licence headers have also been retroactively added where missing (in those files that were missing region tags, if applicable).

[snippet-bot]

Here is the summary of changes.

You are about to add 16 region tags.

• cost-optimization/gke-scheduled-autoscaler/k8s/scheduled-autoscaler/scheduled-autoscale-example.yaml:16, tag gke_scheduled_autoscaler_autoscale_example
• quickstarts/hello-app-redis/manifests/pdb-minavailable.yaml:15, tag gke_quickstarts_hello_app_redis_manifests_pbd_minavailable
• quickstarts/hello-app-redis/manifests/roles.sh:15, tag gke_quickstarts_hello_app_redis_manifests_roles
• quickstarts/languages/dotnet/Dockerfile:15, tag gke_quickstarts_languages_dotnet_dockerfile
• quickstarts/languages/dotnet/Program.cs:15, tag gke_quickstarts_languages_dotnet_program
• quickstarts/languages/go/Dockerfile:15, tag gke_quickstarts_languages_go_dockerfile
• quickstarts/languages/go/helloworld.go:15, tag gke_quickstarts_languages_go_helloworld
• quickstarts/languages/java/Dockerfile:15, tag gke_quickstarts_languages_java_dockerfile
• quickstarts/languages/java/src/main/java/com/example/helloworld/HelloworldApplication.java:15, tag gke_quickstarts_languages_java_helloworld
• quickstarts/languages/nodejs/Dockerfile:15, tag gke_quickstarts_languages_nodejs_dockerfile
• quickstarts/languages/nodejs/index.js:15, tag gke_quickstarts_languages_java_index
• quickstarts/languages/php/Dockerfile:15, tag gke_quickstarts_languages_php_dockerfile
• quickstarts/languages/php/index.php:16, tag gke_quickstarts_languages_php_index
• quickstarts/languages/python/Dockerfile:15, tag gke_quickstarts_languages_python_dockerfile
• quickstarts/languages/python/app.py:15, tag gke_quickstarts_languages_python_app
• security/language-vulns/maven/deployment.yaml:16, tag gke_security_language_vulns_maven_deployment

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[NimJay]

Praise: You even dug up the correct year of creation (of each file). It's a nit, but I appreciate the attention to detail!

[NimJay]

Looks great! Approved. Thanks, again, Olivier!