Update BOOTCLASSPATH environment variable search location

The BOOTCLASSPATH environemnt variable is now set by its own
/etc/classpath file instead of init.environ.rc. Update otapreopt to
match this new location.

Test: manually OTA cuttlefish
Bug: 181182967
Change-Id: Iebdb112cbf1536e6468f8b73f5ff076b893058f9
1 file changed