release: fix on-disc pkg binary symbolic links

Note: As this change was tested during the 13.1 cycle, but never
merged back to stable/12, this change does not warrant an RC3.

Approved by: re (cperciva)
PR: 263574
Sponsored by: Rubicon Communications, LLC ("Netgate")

(cherry picked from commit 68b0a79b7c7ab75597e2511f880238fbf8cfad32)
(cherry picked from commit f398c2d8323c8d8fde80fdb89c6c858b9996c22f)