[OGR provider] Map GeometryCollection of TIN coming from multipart shapefiles to MultiPolygonZ (fixes #29376)

[rouault]

No description provided.

[backporting]

The backport to release-3_4 failed:

Commits ["26dc155da55286aef69496cdd9e92457be3562a0"] could not be cherry-picked on top of release-3_4

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub.
git fetch
# Create new working tree.
git worktree add .worktrees/backport release-3_4
# Navigate to the new directory.
cd .worktrees/backport
# Cherry-pick all the commits of this pull request and resolve the likely conflicts.
git cherry-pick 26dc155da55286aef69496cdd9e92457be3562a0
# Create a new branch with these backported commits.
git checkout -b backport-30024-to-release-3_4
# Push it to GitHub.
git push --set-upstream origin backport-30024-to-release-3_4
# Go back to the original working tree.
cd ../..
# Delete the working tree.
git worktree remove .worktrees/backport

Then, create a pull request where the base branch is release-3_4 and the compare/head branch is backport-30024-to-release-3_4.