Removes the view diff hover links (and strategy icons) in the new views
and removes trailing colons.
In removing the hover links, I have split up the content of their files
(`StrategyTooltipLink` and `SegmentTooltipLink`) into
`Change{Segment|Strategy}Name` and `{Segment|Strategy}Diff`. I have
reverted the existing tooltip files to their state before I began
changing this and added deprecation notices. These old tooltips are only
used by the old components, so we don't need to work on them after all.
In doing this work, I've also updated the strategy change diff to handle
the new functionality (tabs instead of hover)
The removal of the trailing colons (so that it's `adding strategy
gradual rollout` instead of `adding strategy: gradual rollout` is in
preparation for the remaining changes to the header that we're
introducing with this change. The removal of these is not behind a flag,
so I've also done it in the legacy components. This feels like a very
low risk change, so it felt like more work to have to check a flag for
each of the different instances where we use it.
<img width="839" alt="image"
src="https://github.com/user-attachments/assets/b29b8073-c282-4b4b-948f-9a545082ac31"
/>
Use new design for release plans in flag environments.
- Move old ReleasePlanMilestone into Legacy file and update imports
- In the new version, use the same strategy list and item as in the
general strategy list and milestone template creation (components to be
extracted in the future)
- Fix an issue with the border being obscured by overflow by hiding
overflow
