[sw,ci] End of standard support for Ubuntu 22.04 is April 2027

Nobody has claimed this yet.

### Description

We use Ubuntu 22.04 for all of our CI machines, and our current requirements (which includes [`libncursesw5`](https://github.com/lowRISC/opentitan/blob/023bd59e048508f665bb4de133a8c6976066ca13/apt-requirements.txt#L27), which is not packaged for Ubuntu 24.04 or Ubuntu 26.04) only support this version without requiring additional workarounds on the user side.

Ubuntu 22.04 will begin to be deprecated on September 17th 2026 (when deprecation warnings will begin). Brown-outs will start to occur on March 23rd 2027, meaning we may start seeing CI failures then. Support completely stops on April 17th 2027. Many of the packages it ships with will also be out of support by that point in time.

This issue will require solving on all active branches - both `master` and `earlgrey_1.0.0`, and any additional branches or forks that are created.

We should:
* Resolve the issue with system dependencies that aren't available on Ubuntu 24.04 onwards.
* Many developers are already using this version without issue, after working around the `libncursesw5` requirement.
* This will give us 2 more years of standard support.

We could alternatively jump straight to Ubuntu 26.04, which might be preferable as it will give us more years of standard support. However, it may then become harder to maintain compatibility with older systems that wish to run OpenTitan.

Start with apt-requirements.txt and the CI definitions that select Ubuntu 22.04, then identify which dependencies fail on Ubuntu 24.04 or later, especially libncursesw5. Update and validate the configuration across master, earlgrey_1.0.0, and any other active branches so CI runs without user-side workarounds.

Written by the indexing model from the issue text.