Fix Docker (full) build: disable ASM so OpenCV 5's MLAS doesn't break the extern link

The now-actually-running test-native stage caught a pre-existing bug:
OpenCV 5.0.0's vendored MLAS declares and calls MlasHGemmSupported() on
its FP16/GQA path but never defines it, leaving libOpenCvSharpExtern.so
with an undefined reference. windows.yml/linux-arm64.yml/macos.yml already
work around this by dropping CMAKE_ASM_COMPILER so MLAS reports itself
unavailable and DNN falls back to its built-in SGEMM; apply the same fix
here.

Author: shimat

packaging/docker/ubuntu24-dotnet10-opencv5.0.0/Dockerfile

@@ -63,6 +63,12 @@ RUN set -eux; \
     mv opencv_contrib-${OPENCV_VERSION} /opencv_contrib
 
 # Configure, build, and install OpenCV with ccache and parallel build
+#
+# -D CMAKE_ASM_COMPILER="": disables the ASM language so OpenCV 5's vendored
+# MLAS turns off and DNN falls back to its built-in SGEMM. The MLAS FP16/GQA
+# path references MlasHGemmSupported(), which OpenCV 5.0.0 declares and calls
+# but never defines, breaking the extern link with an undefined reference
+# (same fix as windows.yml / linux-arm64.yml / macos.yml).
 RUN --mount=type=cache,target=/root/.ccache \
     set -eux; \
     cmake -G Ninja \
@@ -72,7 +78,8 @@ RUN --mount=type=cache,target=/root/.ccache \
       -D CMAKE_BUILD_TYPE=RELEASE \
       -D CMAKE_C_COMPILER_LAUNCHER=ccache \
       -D CMAKE_CXX_COMPILER_LAUNCHER=ccache \
-      -D CMAKE_INSTALL_PREFIX=/opencv_artifacts; \
+      -D CMAKE_INSTALL_PREFIX=/opencv_artifacts \
+      -D CMAKE_ASM_COMPILER=""; \
     cmake --build /opencv/build --parallel "$(nproc)"; \
     cmake --install /opencv/build; \
     ldconfig