[GCP] Set metric type for GKE, Load Balancing, PubSub, Redis and Storage data streams

[constanca-m]

What does this PR do?

Set metric type for data streams:

• GKE: metric type document can be found here
• Load Balancing: metric type documentation can be found here
• PubSub: metric type documentation can be found here
• Redis: metric type documentation can be found here
• Storage: metric type documentation can be found here.

Important note: all delta metrics are gauge metrics. Related issue for that: elastic/elasticsearch#98171.

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.

Related issues

Relates to #7555.

[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: 2023-09-04T06:48:55.723+0000

• Duration: 19 min 55 sec

Test stats 🧪

Test	Results
Failed	0
Passed	68
Skipped	0
Total	68

🤖 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% (6/6)	💚
Files	100.0% (6/6)	💚
Classes	100.0% (6/6)	💚
Methods	87.826% (101/115)	👎 -12.174
Lines	96.0% (1464/1525)	👍 0.167
Conditionals	100.0% (0/0)	💚

[zmoog]

LGTM.

[elasticmachine]

Package gcp - 2.28.5 containing this change is available at https://epr.elastic.co/search?package=gcp