Move transport client code back to the main target

In ag/9433204 this code was separated into its own library for a feature
that was cancelled. It doesn't make sense to keep it separate anymore.

Test: m
  atest BackupTransportClientTest.java
  atest CtsBackupHostTestCases
Bug: 210083465
Change-Id: I6b5a6bb45563c16b359f0281aac2c28bce03a6fd
diff --git a/services/backup/Android.bp b/services/backup/Android.bp
index ead8aff..b086406 100644
--- a/services/backup/Android.bp
+++ b/services/backup/Android.bp
@@ -19,5 +19,5 @@
     defaults: ["platform_service_defaults"],
     srcs: [":services.backup-sources"],
     libs: ["services.core"],
-    static_libs: ["backuplib", "app-compat-annotations"],
+    static_libs: ["app-compat-annotations"],
 }