Revert "Exec_start derive_classpath on post-fs-data."

Revert "Introduce derive_classpath service."

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: Iefbe057ba45091a1675326e3d5db3f39cc3e2820