[BUG] Ship Join Menu Inconsistency

[PrefabQuasar]

Round ID: 2016

Testmerges:

#2410: 'Ranger Class fixes' by spockye at commit 02fb13f69f
#2446: 'Mining Rework Part 1: First of his Name' by BogCreature at commit b26494c0d0
#2432: 'Goliath Gupdate' by thgvr at commit 355aed11dd
#2488: 'Further mining changes' by thgvr at commit 554721061f
#2469: 'Bump axios from 0.21.1 to 1.6.0 in /tgui' by dependabot[bot] at commit 5df6837a20
#2395: 'ERT Minor Refactor, more ERTs, ERTs can now spawn on subshuttles' by meemofcourse at commit 74a2e3c543

Reproduction:

Currently unsure of the cause of this bug, but the ISV serenity in this round did not re-enter the available ships on the ship join list after it had an extra job slot added via the owner panel. This bug was present across multiple clients.