[MySql] Fix to correct the aggregate function used in dashboard

[agithomas]

• Bug

What does this PR do?

The dashboard uses avg function on field having metric_type value counter. This is not a supported feature. The PR updates to use the max() function instead.

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.
• I have verified that Kibana version constraints are current according to guidelines.

How to test this PR locally

Dashboard testing

Related issues

Screenshots

[elasticmachine]

💚 Build Succeeded

the below badges are clickable and redirect to their specific view in the CI or DOCS

Expand to view the summary

Build stats

• Start Time: 2023-07-05T17:48:47.071+0000

• Duration: 22 min 23 sec

Test stats 🧪

Test	Results
Failed	0
Passed	63
Skipped	0
Total	63

🤖 GitHub comments

Expand to view the GitHub comments

To re-run your PR in the CI, just comment with:

• /test : Re-trigger the build.

[elasticmachine]

🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (2/2)	💚
Files	100.0% (2/2)	💚
Classes	100.0% (2/2)	💚
Methods	92.857% (26/28)	👍
Lines	94.34% (150/159)	👍
Conditionals	100.0% (0/0)	💚

[ritalwar]

LGTM!

[agithomas]

[elasticmachine]

Package mysql - 1.12.4 containing this change is available at https://epr.elastic.co/search?package=mysql