Move package parsing equivalence tests to postsubmit

It can't be guaranteed that these run under the 1 minute presubmit
timeout limit. Now that R is branched, it should be safe to move these
to postsubmit, as the original purpose of validating the new R parsing
logic is now fulfilled.

Also removes the timeout added in a previous change, since it's not
necessary for postsubmit.

Test: atest com.android.server.pm.parsing

Bug: 165227202

Change-Id: I337257f385798818cba06fcad64cc4720932ff1c