Linux: bluetooth.default.so -> libbluetooth.so

Also rename the build goal for both the library.

Bug: 67853426
Test: run Bluetooth
Change-Id: Ic5bd27f10ade0b068057049dd98c09e082cafee1
diff --git a/BUILD.gn b/BUILD.gn
index 618de1c..e471a74 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -23,7 +23,7 @@
 # This pulls in main/BUILD.gn and all of its dependencies.
 group("bluetooth") {
   deps = [
-    "//main:bluetooth.default",
+    "//main:bluetooth",
     "//service:bluetoothtbd",
   ]
 }