[windows] disable vcpkg telemetry

windows-1809/base/Dockerfile

@@ -49,5 +49,5 @@ RUN $vcpkg_dir = 'C:/vcpkg'; \
     git clone -b robofish --single-branch https://git.imp.fu-berlin.de/bioroboticslab/robofish/vcpkg.git; \
     cd $vcpkg_dir; \
     git checkout d61d47c5cac2198bf0262d75742e8a4a38e573d6; \
-    ./scripts/bootstrap.ps1; \
+    ./scripts/bootstrap.ps1 -disableMetrics; \
     [Environment]::SetEnvironmentVariable('VCPKG_DIR', "\"$vcpkg_dir\"", [EnvironmentVariableTarget]::Machine);