Tests on the landingpage with XPath and opacity

[Gustry]

I can confirm that reverting PR #5011 solves the 500.

The purpose was not to merge this PR, but to understand why the E2E was OK on PR #5011.
While there is a Cypress test about the landing page :
https://github.com/3liz/lizmap-web-client/blob/release_3_8/tests/end2end/cypress/integration/projects_homepage-ghaction.js

I can confirm there is a cache issue.

I tried to empty the redis database :

➜ docker exec -it lizmaprelease_3_8_test_redis redis-cli flushall
OK

[Gustry]

CC @mind84 and @rldhont

I just want to trust our E2E test suite and avoid any regression like this one.

[mind84]

Hi @Gustry @rldhont,

I'm preparing the fix for the 500 error. Basically consists in a manual backport of the commit 1e9be74

[rldhont]

I also working on speed up main view to parse only project main data. #5081