This removes fish command completions (but keeps argument completions)
for commands in the `COMPLETIONS_EXCLUSION_LIST` list.
It also removes unnecessary exclusions of `*instal` aliases in command
suggestions in bash and fish completions, since those were removed from
`internal_commands_list.txt` in Homebrew#10229. This makes
`COMPLETIONS_EXCLUSION_LIST` the single source of truth for commands to
exclude from completions.
c5253b23c2