createOperations(): fix incorrect height transformation between 3D promoted RGF93 and CH1903+ (fixes #2541)

[rouault]

No description provided.

[PROJ-BOT]

The backport to 8.0 failed:

The process 'git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-8.0 8.0
# Navigate to the new working tree
cd .worktrees/backport-8.0
# Create a new branch
git switch --create backport-2555-to-8.0
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick 667b7c1f1168e1db51f46a5c89ddbea28e862115
# Push it to GitHub
git push --set-upstream origin backport-2555-to-8.0
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-8.0

Then, create a pull request where the base branch is 8.0 and the compare/head branch is backport-2555-to-8.0.

[rouault]

Manually backported to 8.0 (and removing the "backport 8.0" label as it is obviously broken)