[ISSUE][DOCS] Multiple issues with Terrain Surface Materials List Component documentation page

[LB-ArturZieba]

Describe the issue

Terrain Gem under the Provider section is broken, mentioned in this issue: https://github.com/o3de/o3de.org/issues/1653.

Terrain Surface Materials List component image under the Properties section is deprecated: Current:

There is no information about existing properties of the Terrain Physics Heightfield Collider component:

• Default Material
  • Material asset (not to mistake with Material Mappings > Material asset)

Gradient to Material Mappings property in the table under the Properties section is currently named Material Mappings.

Surface Tag property Default value in the Properties table should be (unassigned).

Impacted page(s)

https://www.o3de.org/docs/user-guide/components/reference/terrain/surface-material-list/

Expected experience

Documentation contains current information.

[FiniteStateGit]

Link to Terrain Gem fixed in #1700.