Remove lottie from the default manifest.

It's not currently used, and upstream it putting out regular updates
that we're wasting time tracking.

It'll require a manifest change to re-enable anyway (because it now uses
okio, which hasn't gone through go/android-3p approval), so there's no
point keeping it in the manifest until/unless that happens.

Change-Id: Id116bec3809cc376bd84f29e8f502378651349ca

default.xml

@@ -285,7 +285,6 @@
   <project path="external/linux-kselftest" name="platform/external/linux-kselftest" groups="vts,pdk" />
   <project path="external/llvm" name="platform/external/llvm" groups="pdk" />
   <project path="external/lmfit" name="platform/external/lmfit" groups="pdk" />
-  <project path="external/lottie" name="platform/external/lottie" groups="pdk" />
   <project path="external/lua" name="platform/external/lua" groups="pdk" />
   <project path="external/ltp" name="platform/external/ltp" groups="vts,pdk" />
   <project path="external/lz4" name="platform/external/lz4" groups="pdk" />