ci: Add Conan retry

[legleux]

High Level Overview of Change

Bumps Conan's download retry settings so that transient upstream failures (occasionally 502s from GitHub when a recipe's source() step fetches an archive) no longer fail the "Build dependencies" step on the first hiccup.

Adds to global.conf

• tools.files.download:retry=5 (default: 2)
• tools.files.download:retry_wait=10 (default: 1 second)

Context of Change

The xrplf Conan remote at conan.ripplex.io mirrors recipes and prebuilt binaries but does not mirror upstream source archives. Whenever conan install --build=missing encounters a package_id that has no prebuilt (new compiler, new sanitizer profile, new option combination), Conan falls back to building from source, which fetches the tarball directly from the recipe's upstream URL. GitHub's archive host has been returning intermittent 502s, which currently fail the job immediately on the second attempt.

Future Tasks

It is possible to mirror the source to Artifactory also if we want and configure core.sources:download_urls to point there.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.1%. Comparing base (aa5e4ff) to head (f5d53b1).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@            Coverage Diff            @@
##           develop   #7147     +/-   ##
=========================================
- Coverage     82.1%   82.1%   -0.0%     
=========================================
  Files         1010    1010             
  Lines        76203   76205      +2     
  Branches      7403    7406      +3     
=========================================
- Hits         62570   62562      -8     
- Misses       13633   13643     +10     

see 5 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[mathbunnyru]

Nice, thanks!