chore(analysis/convex/exposed): downgrade imports (#18186)
Everything in this file was stated for
```lean
[normed_linear_ordered_field 𝕜]
```
but would have worked for
```lean
[topological_space 𝕜] [linear_ordered_ring 𝕜] [order_topology 𝕜]
```
and I have generalized even further where it was easy.
