[roll] Roll fuchsia [starnix][kernel] Disassociate TTY on session leader exit

When a session leader terminates on Linux, it disassociates itself from
its controlling terminal and sends SIGHUP/SIGCONT to the foreground
process group.

Upcoming changes to the Task/ThreadGroup lifecycle delegate resource
management to RCU, which defers drops. Those changes uncovered the lack
of explicit disassociation.

Starnix has relied on the Session object being dropped to release the
terminal, which could leave the terminal associated if other references
to the Session (or terminal descriptors) remained, preventing future
sessions from reusing the terminal.

Original-Original-Bug: 297440106
Test: starnix_gvisor_pty_test
Original-Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1609148
Original-Original-Revision: a748933494402f50cd4f16bf18d25e1a7ff23473
GitOrigin-RevId: a1c341ec1681fc999d26d160a018af02d04a5a16
Change-Id: Iafc7940265237c9275c5357e236c5761f27d729d
Reviewed-on: https://fuchsia-review.googlesource.com/c/integration/+/1617088
Cr-Commit-Position: refs/heads/main@{#192941}