Bug 1581971: Part 4 - Change Android's priority debugger to lldb; r=ahal

`./mach run --debug` is being enabled for `lldb` only, so it should be
the preferred debugger instead of `gdb`.

Differential Revision: https://phabricator.services.mozilla.com/D94382

testing/mozbase/mozdebug/mozdebug/mozdebug.py

@@ -51,7 +51,7 @@ _DEBUGGER_PRIORITIES = {
     "win": ["devenv.exe", "wdexpress.exe"],
     "linux": ["gdb", "cgdb", "lldb"],
     "mac": ["lldb", "gdb"],
-    "android": ["gdb"],
+    "android": ["lldb"],
     "unknown": ["gdb"],
 }