MRE updates of openvpn for noble

[Bryce Harrington]

This bug tracks an update for the OpenVPN package, moving to versions:

* Noble (24.04): OpenVPN 2.6.10
* Mantic (23.10): OpenVPN 2.6.10
* Jammy (22.04): OpenVPN 2.5.10

Note that openvpn does not have an accepted micro-release exception. However, the SRU team has agreed to consider further releases given a full knowledge and possible mitigation of backwards-incompatible changes. See https://lists.ubuntu.com/archives/ubuntu-release/2023-July/005688.html

[Upstream Changes]

[Test Plan]

DEP-8 Tests:
server-setup-with-ca - creates and tests an OpenVPN server setup with its own certificate authority
server-setup-with-static-key - creates and tests an OpenVPN server setup using a static key for authentication

[Regression Potential]

Upstream has an extensive build and integration test suite. So regressions would likely arise from a change in interaction with Ubuntu-specific integrations.