Fix order of 'kill' arguments in killport function.

[matthewdale]

The versions of kill on the platforms we commonly use (Ubuntu, RHEL, macOS) expect the -SIGKILL flag to come before the PID arguments.

Ubuntu

$ kill "1234567890" -SIGKILL
-bash: kill: (1234567890) - No such process
-bash: kill: -SIGKILL: arguments must be process or job IDs

With -SIGKILL first:

$ kill -SIGKILL "1234567890"
-bash: kill: (1234567890) - No such process

RHEL

$ kill "1234567890" -SIGKILL
-bash: kill: (1234567890) - No such process
-bash: kill: -SIGKILL: arguments must be process or job IDs

With -SIGKILL first:

$ kill -SIGKILL "1234567890"
-bash: kill: (1234567890) - No such process

macos

❯ kill "1234567890" -SIGKILL
kill: kill 1234567890 failed: no such process
kill: illegal pid: -SIGKILL

With -SIGKILL first:

❯ kill -SIGKILL "1234567890"
kill: kill 1234567890 failed: no such process