Fix `trap` in a few shell scripts

Fix `trap` in a few shell scripts

The original `trap` lines in these scripts are incomplete: in case of
any signal, they delete the working directory but let the script run to
completion, which is useless because it will only proceed to complain
about the working directory being removed.  Add `exit` there, with the
original exit value (not rm's).

Since this is mostly just cosmetic, no backpatch.

Discussion: https://postgr.es/m/20220913181002.hzsosy7qkemb7ky7@alvherre.pgsql