Revert "Revert "releasetools: Allow using futility-host to sign old TF.zip.""

This reverts commit d6145b6a160a7c171269d9408a675d8ff4f08283.

The cause of the earlier breakage has been identified and fixed by
commit 4b577413ff5c43e9b857f5c1685d6909e7ca27ba.

Bug: 35467608
Test: lunch ryu-userdebug; m dist otatools-package
1 file changed