Cleanup `tmp-*` directories in the plugin directory from previous crashes

[pskrbasu]

There's a temp directory in the plugins directory that is not deleted after plugin installation:

drwxr-xr-x 4 root root 4096 Jun  4 02:59 .
drwxr-xr-x 3 root root 4096 Jun  4 03:00 ..
drwxr-xr-x 3 root root 4096 Jun  4 02:58 hub.tailpipe.io
drwxr-xr-x 2 root root 4096 Jun  4 02:27 tmp-8bfb-49de-a26e
-rw-r--r-- 1 root root 2179 Jun  4 02:59 versions.json

The content is:

mp-8bfb-49de-a26e# ls -la
total 22048
drwxr-xr-x 2 root root    4096 Jun  4 02:27 .
drwxr-xr-x 4 root root    4096 Jun  4 02:59 ..
-rw-r--r-- 1 root root 8911974 Jun  4 02:37 tailpipe-plugin-core_darwin_amd64.gz
-rw-r--r-- 1 root root 8528628 Jun  4 02:36 tailpipe-plugin-core_darwin_arm64.gz
-rw-r--r-- 1 root root 5110886 Jun  4 02:36 tailpipe-plugin-core_linux_amd64.gz

We probably should clean up old tmp-* directories from previous crashes.