Revert "Introduce derive_classpath."

Revert submission 1602413-derive_classpath

Bug: 180105615
Fix: 183079517
Reason for revert: SELinux failure leading to *CLASSPATH variables not being set in all builds

Reverted Changes:
I6e3c64e7a:Introduce derive_classpath service.
I60c539a8f:Exec_start derive_classpath on post-fs-data.
I4150de69f:Introduce derive_classpath.

Change-Id: I17e2cd062d8fddc40250d00f02e40237ad62bd6a
diff --git a/apex/com.android.sdkext-file_contexts b/apex/com.android.sdkext-file_contexts
index 551a12c..2d59dda 100644
--- a/apex/com.android.sdkext-file_contexts
+++ b/apex/com.android.sdkext-file_contexts
@@ -1,3 +1,2 @@
-(/.*)?                       u:object_r:system_file:s0
-/bin/derive_classpath        u:object_r:derive_classpath_exec:s0
-/bin/derive_sdk              u:object_r:derive_sdk_exec:s0
+(/.*)?                u:object_r:system_file:s0
+/bin/derive_sdk       u:object_r:derive_sdk_exec:s0