Fix regression not aborting transaction on error, and re-edit some error responses (#10612)

1. Disk error and slave count checks didn't flag the transactions or counted correctly in command stats (regression from #10372  , 7.0 RC3)
2. RM_Call will reply the same way Redis does, in case of non-exisitng command or arity error
3. RM_WrongArtiy will consider the full command name
4. Use lowercase 'u' in "unknonw subcommand" (to align with "unknown command")

Followup work of #10127