adb: Drop -W (wait for app) from am start for faster --uid filt…

…er (#137)

This effectively reverts commit bf478ad
(#118) without touching code improvements elsewhere.  `-W` makes app
start-up significantly slower, sometimes leaving the user wait up to 10
seconds even if the app has already started and crashed without showing
any `logcat` output.  It has now become unnecessary since using the app
`uid` as filter in #131, which is always available as long as the app
is installed and doesn't rely on a running (**before** having crashed!)
executable for a process id.

xbuild/src/devices/adb.rs

@@ -98,7 +98,6 @@ impl Adb {
             .shell(device, None)
             .arg("am")
             .arg("start")
-            .arg("-W")
             .arg("-a")
             .arg("android.intent.action.MAIN")
             .arg("-n")