ci: RelWithDebInfo, CMake presets and the shared HPC base template

[mcocdawc]

Description

• Build type Release → RelWithDebInfo.
• New CMakePresets.json: ci (ENABLE_EXTRA_TESTS, ENABLE_ECCODES_OMP_THREADS) and eckit-geo, which inherits it and adds ENABLE_GEOGRAPHY, ENABLE_ECKIT_GEO. The matrix options value now names the preset, replacing the options-to-flags case step in the action and the {% if %} in the HPC recipe. The runner lane now builds with EXTRA_TESTS and OMP_THREADS too, as HPC already did.
• .ci/hpc/build.sh.j2 extends the shared base template and overrides only the test (two-pass ctest with definitions/samples paths) and install (DESTDIR staging) blocks; HPC legs keep time = "01:30:00".

Needs ecmwf/ci-infrastructure#63 on main first. Part of the coordinated sync-branch/update-cmake-build-type change across ecbuild, stack-dependencies, eckit, eccodes and ecflow.

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Contributor Declaration

By opening this pull request, I affirm the following:

• All authors agree to the Contributor License Agreement.
• The code follows the project's coding standards.
• I have performed self-review and added comments where needed.
• I have added or updated tests to verify that my changes are effective and functional.
• I have run all existing tests and confirmed they pass.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.68%. Comparing base (46b66c9) to head (09575db).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #558   +/-   ##
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  Coverage    87.68%   87.68%           
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  Files          856      856           
  Lines        63975    63975           
  Branches     11395    11395           
========================================
  Hits         56094    56094           
  Misses        7881     7881           

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