[pod-gateway] Change default openvpn port to 1194

[angelnu]

Description of the change

Change default openvpn port to 1194 as this is the default for UDP.

Benefits

Be consistent: use matching default port for UDP.

Possible drawbacks

Changing defaults might affect some users.

Applicable issues

• fixes #1525

Additional information

Checklist

• [x] Title of the PR starts with chart name (e.g. [home-assistant])
• [x] Chart version bumped in Chart.yaml according to semver.
• [x] Chart artifacthub.io/changes changelog annotation has been updated in Chart.yaml. See Artifact Hub documentation for more info.
• [x] Variables have been documented in the values.yaml file.