sagemathgh-39210: Switch devcontainer to use meson

    
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URL: sagemath#39210
Reported by: Tobias Diez
Reviewer(s): Dima Pasechnik

.devcontainer/onCreate-conda.sh

@@ -10,5 +10,4 @@ mamba env create -y --file environment-3.11-linux.yml || mamba env update -y --f
 conda init bash
 
 # Build sage
-conda run -n sage-dev ./bootstrap
-conda run -n sage-dev pip install --no-build-isolation -v -v -e ./src
+conda run -n sage-dev pip install --no-build-isolation -v -v -e .