### Description of the change
Removes checks for mariadb and mysql from _helpers.tpl
### Benefits
Fixes the helm-chart version 8.0.0 if using a external database
### Applicable issues
- fixes#420
- fixes#419
Reviewed-on: https://gitea.com/gitea/helm-chart/pulls/421
Reviewed-by: justusbunsi <justusbunsi@noreply.gitea.io>
Reviewed-by: John Olheiser <john+gitea@jolheiser.com>
Reviewed-by: delvh <dev.lh@web.de>
Reviewed-by: yardenshoham <yardenshoham@noreply.gitea.io>
Co-authored-by: Maximilian Marschall <maximilian.marschall@3xm.at>
Co-committed-by: Maximilian Marschall <maximilian.marschall@3xm.at>
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