Remove legacy-test and legacy-android-test targets

Fixes up the android.test.legacy target to stop using sources directly
now that the issue with android.test.runner-minus-junit not being able
to be built against the SDK has been resolved.

Also, fixes a couple of comments.

Bug: 63127064
Test: make checkbuild
Change-Id: If38fa0d87b36343896e97efb2269ac070810db84

test-mock/Android.bp

@@ -30,19 +30,3 @@ java_sdk_library {
     srcs_lib_whitelist_pkgs: ["android"],
     compile_dex: true,
 }
-
-// Build the android.test.mock_static library
-// ==========================================
-// This is only intended for inclusion in the legacy-android-test.
-// Must not be used elewhere.
-java_library_static {
-    name: "android.test.mock_static",
-
-    java_version: "1.8",
-    srcs: ["src/**/*.java"],
-
-    no_framework_libs: true,
-    libs: [
-        "framework",
-    ],
-}