fix: mapfish print and tile cache optimizations

[wp99cp]

Backports the print URL fix and the tile cache reverse proxy load-balancing optimizations to the master branch.

[Copilot]

Pull request overview

Backports two production-facing fixes: updating the Mapfish print endpoint to the correct print-app name, and optimizing the Nginx tile-cache reverse proxy to better handle heavy load by introducing upstream load-balancing and connection reuse.

Changes:

• Update Mapfish print URL to target the swisstopo print-app (/print/swisstopo/report.pdf).
• Add Nginx upstream pool for wmts*.geo.admin.ch with keepalive + HTTP/1.1 proxying, and tune keepalive settings.
• Adjust tile-cache image build to create the cache directory and set it owned by the nginx user.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
tile_caching/nginx.conf	Adds upstream load-balancing and keepalive-related proxy optimizations for WMTS tile requests.
tile_caching/Dockerfile	Ensures the cache directory exists and is owned by nginx in the built image.
backend/automatic_walk_time_tables/map_downloader/create_map.py	Fixes Mapfish print endpoint path to use the swisstopo print-app.

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