Disable prebuilt_test

The prebuilt tests are accidentally writing a .soong.environment file to
the build/soong/android directory, disable them until TestConfig() is
fixed to prevent writing to the source tree.

Bug: 31800129
Test: m -j, make sure .soong.environment is not written to the source tree
Change-Id: I3b7d47e42111ecababe275b7a9ff0d08bcebfc7a

Android.bp

@@ -82,7 +82,7 @@ bootstrap_go_package {
     ],
     testSrcs: [
         "android/paths_test.go",
-        "android/prebuilt_test.go",
+        //"android/prebuilt_test.go",
     ],
 }