Fix #714: large file upload tuning as configuration

[antoinetran]

Description of the change

Fix https://github.com/nextcloud/helm/issues/714

Benefits

Can now upload large file. And if the default values are not enough, can override them in values.yaml.

Possible drawbacks

Applicable issues

• fixes #

Additional information

Checklist

• [X] I have read the CONTRIBUTING.md doc.
• [X] DCO has been signed off on the commit.
• [X] Chart version bumped in Chart.yaml according to semver.
• [ ] (optional) Parameters are documented in the README.md