Move jsch and objectify to directly under third_party

We used to have a lot more vendored third_party dependencies, but now we're only going to have three that we know of, so this java/javatests distinction isn't necessary.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=177631319

third_party/java/jsch/BUILD

@@ -1,8 +0,0 @@
-package(default_visibility = ["//visibility:public"])
-
-licenses(["notice"])  # BSD
-
-java_library(
-    name = "jsch",
-    exports = ["//third_party/java/jsch/v0_1_53"],
-)

third_party/java/jsch/v0_1_53/BUILD

@@ -1,15 +0,0 @@
-package_group(
-    name = "specific_version",
-    packages = ["//third_party/java/jsch"],
-)
-
-package(default_visibility = ["//visibility:public"])
-
-licenses(["notice"])  # BSD
-
-java_import(
-    name = "v0_1_53",
-    jars = ["jsch-0.1.53.jar"],
-    srcjar = "jsch-0.1.53-src.jar",
-    deps = ["@com_jcraft_jzlib"],
-)