Dockerfile: remove redundant Android SDK packages

Updates tailscale/tailscale#424

Signed-off-by: Elias Naur <mail@eliasnaur.com>

Dockerfile

@@ -25,7 +25,7 @@ RUN echo y | $ANDROID_HOME/tools/bin/sdkmanager --update
 RUN echo y | $ANDROID_HOME/tools/bin/sdkmanager 'platforms;android-29'
 RUN echo y | $ANDROID_HOME/tools/bin/sdkmanager 'build-tools;29.0.0'
 RUN echo y | $ANDROID_HOME/tools/bin/sdkmanager 'extras;android;m2repository'
-RUN echo y | $ANDROID_HOME/tools/bin/sdkmanager 'ndk-bundle'
+RUN echo y | $ANDROID_HOME/tools/bin/sdkmanager 'ndk;20.0.5594570'
 
 # Get Go stable release
 WORKDIR $HOME
@@ -36,10 +36,6 @@ RUN tar -xzf go${GO_VERSION}.linux-amd64.tar.gz && mv go goroot
 ENV GOROOT $HOME/goroot
 ENV PATH $PATH:$GOROOT/bin:$HOME/bin
 
-RUN echo y | $ANDROID_HOME/tools/bin/sdkmanager 'platforms;android-26'
-RUN echo y | $ANDROID_HOME/tools/bin/sdkmanager 'ndk;20.1.5948944'
-RUN echo y | $ANDROID_HOME/tools/bin/sdkmanager 'ndk;20.0.5594570'
-
 # TODO: pre-install Grade 6.3 so gogio doesn't download it later at runtime at the build.sh step.
 # TODO: ... likewise, all this:
 # Checking the license for package Android SDK Build-Tools 28.0.3 in /build/android-sdk/licenses