Remove short flag from history purge command. (#5242)

The command `minder history purge` supports specifying a custom batch
size via `--batch-size/-s` option. The short version `-s` overlaps
with the short version of `--db-sslmode`, which is a root-level option.

This change solves the overlap by removing the short option from
`minder history purge`.

cmd/server/app/history_purge.go

@@ -169,6 +169,6 @@ func deleteEvaluationHistory(
 
 func init() {
 	historyCmd.AddCommand(historyPurgeCmd)
-	historyPurgeCmd.Flags().UintP("batch-size", "s", 1000, "Size of the deletion batch")
+	historyPurgeCmd.Flags().UintP("batch-size", "", 1000, "Size of the deletion batch")
 	historyPurgeCmd.Flags().Bool("dry-run", false, "Avoids deleting, printing out details about the operation")
 }