helm: cleanup helm chart, now in mastodon/chart (#21801)

.github/workflows/test-chart.yml

.gitignore

.prettierignore

chart/.helmignore

chart/Chart.lock

chart/Chart.yaml

chart/README.md

chart/dev-values.yaml

chart/templates/NOTES.txt

chart/templates/_helpers.tpl

chart/templates/configmap-env.yaml

chart/templates/cronjob-media-remove.yaml

chart/templates/deployment-sidekiq.yaml

chart/templates/deployment-streaming.yaml

chart/templates/deployment-web.yaml

chart/templates/ingress.yaml

chart/templates/job-assets-precompile.yaml

chart/templates/job-chewy-upgrade.yaml

chart/templates/job-create-admin.yaml

chart/templates/job-db-migrate.yaml