[lldb] remove TestRegisters.py skip

This test was skipped to get the bots green, but it is passing
on my desktop.  I'd like to see if it is failing on the bots at
this point, and if so, how.

Author: jasonmolenda

lldb/test/API/commands/register/register/register_command/TestRegisters.py

@@ -42,7 +42,6 @@ def get_sme_available(self):
     @skipIfiOSSimulator
     @skipIf(archs=no_match(["amd64", "arm$", "i386", "x86_64"]))
     @expectedFailureAll(oslist=["freebsd", "netbsd"], bugnumber="llvm.org/pr48371")
-    @skipIf(bugnumber="rdar://159864305")
     def test_register_commands(self):
         """Test commands related to registers, in particular vector registers."""
         self.build()