Deprecate Snapshot build

Existing snapshot code will no longer work from VNDK deprecation, but it
can give confusion to users if we keep code for the snapshot - and it
adds complexity on existing code while it is not in use. This change
removes all snapshot definition except host snapshot and its usage.

Bug: 330100430
Bug: 332986564
Test: AOSP CF build succeeded
Change-Id: Ieb6fa43d5e38315c662ce997bc305b744b367c24

etc/Android.bp

@@ -9,16 +9,13 @@ bootstrap_go_package {
         "blueprint",
         "soong",
         "soong-android",
-        "soong-snapshot",
     ],
     srcs: [
         "prebuilt_etc.go",
-        "snapshot_etc.go",
         "install_symlink.go",
     ],
     testSrcs: [
         "prebuilt_etc_test.go",
-        "snapshot_etc_test.go",
         "install_symlink_test.go",
     ],
     pluginFor: ["soong_build"],