benchmark is missing jq and kubectl

<!--
Please read this!

Before opening a new issue, make sure to search for keywords in the issues
filtered by the "Bug" label.

Issue tracker:

- https://gitlab.com/ongresinc/stackgres/-/issues?label_name=Bug

and verify the issue you're about to submit isn't a duplicate.
-->
### Summary

<!--(Summarize the bug encountered concisely)-->

When running a benchmark with SGDBOps, it keeps complaining about the missing `kubectl` and `jq` tools.

### Current Behaviour 


#### Steps to reproduce

1. create a cluster with pg 12, like below:

```yaml
apiVersion: stackgres.io/v1
kind: SGCluster
metadata:
  name: backup-test
  namespace: default
spec:
  instances: 2
  pods:
    persistentVolume:
      size: 10Gi
      storageClass: gp2
  postgres:
    version: "12.8"
```

1. wait for the cluster be up and running
1. create the sgdbops:

```yaml
apiVersion: stackgres.io/v1
kind: SGDbOps
metadata:
  name: database-fill
  namespace: default
spec:
  benchmark:
    pgbench:
      concurrentClients: 1
      databaseSize: 8Gi
      duration: P0DT0H1M0S
      threads: 1
      usePreparedStatements: false
    type: pgbench
  maxRetries: 0
  op: benchmark
  sgCluster: backup-test
```


When checking the logs, lots of messages like this appears:

```
++ kubectl get '' -n '' '' -o json
/usr/local/bin/shell-utils: line 142: kubectl: command not found
+ RESULT=
++ jq -R .
/usr/local/bin/shell-utils: line 143: jq: command not found
++ printf %s 'Database pgbench_6166fbe8 created'
```

When checking the job, I've found that is using the images below:

```
❯ kubectl get jobs.batch database-fill-benchmark-fea9f890aa0a46dd-0 -o json | gojq '.spec.template.spec.initContainers |map( { name: .name, image: .image })'
[
  {
    "image": "docker.io/ongres/kubectl:v1.19.14-build-6.6",
    "name": "set-dbops-running"
  }
]

❯ kubectl get jobs.batch database-fill-benchmark-fea9f890aa0a46dd-0 -o json | gojq '.spec.template.spec.containers |map( { name: .name, image: .image })'
[
  {
    "image": "docker.io/ongres/patroni:v2.1.1-pg12.8-build-6.6",
    "name": "run-dbops"
  },
  {
    "image": "docker.io/ongres/kubectl:v1.19.14-build-6.6",
    "name": "set-dbops-result"
  }
]
```

### Expected Behaviour

No errors from `kubectl` or `jq`.


### Possible Solution

Since both `postgres-util` and `patroni` doesn't have the binaries installed will be necessary to use another image.

Use the `kubectl` image or mount/copy the binaries from it.

```
❯ docker run --rm -it docker.io/ongres/kubectl:v1.19.14-build-6.6 bash
bash-4.4$ jq --version
jq-1.5
bash-4.4$ kubectl version
Client Version: version.Info{Major:"1", Minor:"19", GitVersion:"v1.19.14", GitCommit:"0fd2b5afdfe3134d6e1531365fdb37dd11f54d1c", GitTreeState:"clean", BuildDate:"2021-08-11T18:07:41Z", GoVersion:"go1.15.15", Compiler:"gc", Platform:"linux/amd64"}
The connection to the server localhost:8080 was refused - did you specify the right host or port?
```

### Environment

- StackGres version: 

```
❯ kubectl get deployments -n stackgres stackgres-operator --template '{{ printf "%s\n" (index .spec.template.spec.containers 0).image }}'
stackgres/operator:1.0.0-RC1
```
<!-- if you have used helm, you can use:  `helm get notes -n stackgres stackgres-operator` 
more generic: `kubectl get deployments -n stackgres stackgres-operator --template '{{ printf "%s\n" (index .spec.template.spec.containers 0).image }}'`
-->
- Kubernetes version:

```
❯ kubectl version
Client Version: version.Info{Major:"1", Minor:"22", GitVersion:"v1.22.0", GitCommit:"c2b5237ccd9c0f1d600d3072634ca66cefdf272f", GitTreeState:"clean", BuildDate:"2021-08-04T17:56:19Z", GoVersion:"go1.16.6", Compiler:"gc", Platform:"darwin/amd64"}
Server Version: version.Info{Major:"1", Minor:"20+", GitVersion:"v1.20.7-eks-d88609", GitCommit:"d886092805d5cc3a47ed5cf0c43de38ce442dfcb", GitTreeState:"clean", BuildDate:"2021-07-31T00:29:12Z", GoVersion:"go1.15.12", Compiler:"gc", Platform:"linux/amd64"}
WARNING: version difference between client (1.22) and server (1.20) exceeds the supported minor version skew of +/-1
```

<!--(use `kubectl version`) -->
- Cloud provider or hardware configuration: AWS with EKS


### Relevant logs and/or screenshots

<!-- (Paste any relevant logs - please use code blocks (```) to format console output,
logs, and code as it's very hard to read otherwise.) -->

* [dbops-full-log.txt](/uploads/d50c6e60d7e370fc720b2088c4562680/dbops-full-log.txt)
* [cluster-objects.yaml](/uploads/7ca1789084f84b2793fd59f5afa18d6e/cluster-objects.yaml)

**Acceptance criteria:**
- [ ] Fix the bug 
- [ ] create the test

Story points: 16.0