MPD: disable 0.21.19 (42) and 0.21.20 (43)

Also disable AUM until someone figures out what's going wrong.

metadata/org.musicpd.yml

@@ -204,6 +204,7 @@ Builds:
 
   - versionName: 0.21.19
     versionCode: 42
+    disable: crashes on start
     commit: v0.21.19
     sudo:
       - apt-get update || apt-get update
@@ -217,10 +218,11 @@ Builds:
       - ../../android/build.py $$SDK$$ $$NDK$$ arm64-v8a
       - meson configure
       - ninja android/apk/mpd-unsigned.apk
-    ndk: r18b
+    ndk: r20b
 
   - versionName: 0.21.20
     versionCode: 43
+    disable: crashes on start
     commit: v0.21.20
     sudo:
       - apt-get update || apt-get update
@@ -234,12 +236,18 @@ Builds:
       - ../../android/build.py $$SDK$$ $$NDK$$ arm64-v8a
       - meson configure
       - ninja android/apk/mpd-unsigned.apk
-    ndk: r18b
+    ndk: r20b
 
-MaintainerNotes: armeabi-v7a and x86 versions crash on daemon start, so we provide
+MaintainerNotes: |-
+    armeabi-v7a and x86 versions crash on daemon start, so we provide
     only arm64-v8a. See https://gitlab.com/fdroid/fdroiddata/issues/1583.
 
-AutoUpdateMode: Version v%v
+    0.21.19 and 0.21.20 crash on mpd start with "java.lang.RuntimeException:
+    invalid channel for service notification" (Android 8.1) or
+    "java.lang.SecurityException: Permission Denial: startForeground requires
+    android.permission.FOREGROUND_SERVICE" (Android 9.0).
+
+AutoUpdateMode: None
 UpdateCheckMode: Tags
 CurrentVersion: 0.21.20
 CurrentVersionCode: 43