Drop snapcraft-preload from snap package

The multiprocessing python module should function correctly with the newer method of using a private shared memory for the snap (see the plug `shared-memory` with `private` set to `true`).

snap/snapcraft.yaml

@@ -191,21 +191,13 @@ parts:
     source: snap/local
     plugin: dump
 
-  snapcraft-preload:
-    source: https://github.com/sergiusens/snapcraft-preload.git
-    plugin: cmake
-    cmake-parameters:
-      - -DCMAKE_INSTALL_PREFIX=/
-    build-packages:
-      - on amd64:
-        - gcc-multilib
-        - g++-multilib
+plugs:
+  shared-memory:
+    private: true
 
 apps:
   opendronemap:
     command: odm/run.sh
-    command-chain:
-      - bin/snapcraft-preload # Fixes multiprocessing python module
     environment:
       # Ensure libraries are found
       LD_LIBRARY_PATH: $SNAP/usr/lib/$SNAPCRAFT_ARCH_TRIPLET/blas:$SNAP/usr/lib/$SNAPCRAFT_ARCH_TRIPLET/lapack:$LD_LIBRARY_PATH