Respect configuration value cmake.parallelJobs in defaultBuildPreset

### Brief Issue Summary

In the extension settings there is a value Parallel Jobs to specify the value for `--parallel`.
It also has the nice feature for auto detection when 0 is specified.

When CMake configure presets are used without CMake build presets, a very minimal defaultBuildPreset (name from extension code) is used, which uses only 1 parallel job, regardless of the extension settings.

I think it would make more sense to respect the configuration value cmake.parallelJobs in this case, especially with the auto detection with value 0. Otherwise it seems (afaik) like I have to create basically an empty build preset for each configuration preset, just to specify the number of parallel jobs.

### CMake Tools Diagnostics

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### Debug Log

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### Additional Information

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Start by locating the extension code that creates the minimal defaultBuildPreset when configure presets lack build presets, then trace how cmake.parallelJobs is read for normal builds. The change is done when this fallback respects the configured parallel-job value, including automatic detection when it is 0.

Written by the indexing model from the issue text.