Fix redis-cli --count (for --scan, --bigkeys, etc) was ignored unless…

… --pattern was also used (#13092)

The --count option for redis-cli has been released in redis 7.2.
redis/redis#12042
But I have found in code, that some logic was missing for using this
'count' option.

```
static redisReply *sendScan(unsigned long long *it) {
    redisReply *reply;

    if (config.pattern)
        reply = redisCommand(context, "SCAN %llu MATCH %b COUNT %d",
            *it, config.pattern, sdslen(config.pattern), config.count);
    else
        reply = redisCommand(context,"SCAN %llu",*it);
```

The intention was being able to using scan count.
But in this case, the --count will be only applied when 'pattern' is
declared.
So, I had fix it simply, to be worked properly - even if --pattern
option is not being used.

I tested it simply with time() command several times, and I could see it
works as intended with this commit.
The examples of test results are below:
```

time(./redis-cli -a $AUTH -p $PORT -h $HOST --scan >/dev/null 2>/dev/null)

real    0m1.287s
user    0m0.011s
sys     0m0.022s

time(./redis-cli -a $AUTH -p $PORT -h $HOST --scan --count 1000 >/dev/null 2>/dev/null)

real    0m1.117s
user    0m0.011s
sys     0m0.020s

time(./redis-cli -a $AUTH -p $PORT -h $HOST --scan --count 1000 --pattern "hash:*" >/dev/null 2>/dev/null)

real    0m0.045s
user    0m0.002s
sys     0m0.002s
```

```
time(./redis-cli -a $AUTH -p $PORT -h $HOST --scan >/dev/null 2>/dev/null)

real    0m1.084s
user    0m0.008s
sys     0m0.024s

time(./redis-cli -a $AUTH -p $PORT -h $HOST --scan --count 1000 >/dev/null 2>/dev/null)

real    0m0.043s
user    0m0.000s
sys     0m0.004s

time(./redis-cli -a $AUTH -p $PORT -h $HOST --scan --count 1000 --pattern "hash:*" >/dev/null 2>/dev/null)

real    0m0.031s
user    0m0.002s
sys     0m0.002s
```

Thanks a lot.

(cherry picked from commit 763827c)