[8.2] Add tags field to internal_metrics data stream (backport #8292)

[mergify]

This is an automatic backport of pull request #8292 done by Mergify.
Cherry-pick of 6c84207 has failed:

On branch mergify/bp/8.2/pr-8292
Your branch is up to date with 'origin/8.2'.

You are currently cherry-picking commit 6c842076.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   apmpackage/apm/data_stream/internal_metrics/fields/ecs.yml

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   apmpackage/apm/changelog.yml

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

---

Mergify commands and options

More conditions and actions can be found in the documentation.

You can also trigger Mergify actions by commenting on this pull request:

• @Mergifyio refresh will re-evaluate the rules
• @Mergifyio rebase will rebase this PR on its base branch
• @Mergifyio update will merge the base branch into this PR
• @Mergifyio backport <destination> will backport this PR on <destination> branch

Additionally, on Mergify dashboard you can:

• look at your merge queues
• generate the Mergify configuration with the config editor.

Finally, you can contact us on https://mergify.com

[apmmachine]

💚 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: 2022-06-03T04:10:09.281+0000

• Duration: 28 min 58 sec

Test stats 🧪

Test	Results
Failed	0
Passed	3975
Skipped	13
Total	3988

🤖 GitHub comments

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

• /test : Re-trigger the build.

• /hey-apm : Run the hey-apm benchmark.

• /package : Generate and publish the docker images.

• /test windows : Build & tests on Windows.

• run elasticsearch-ci/docs : Re-trigger the docs validation. (use unformatted text in the comment!)

[apmmachine]

🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (43/43)	💚
Files	91.878% (181/197)	👍
Classes	93.392% (424/454)	👍
Methods	89.265% (1081/1211)	👍
Lines	77.345% (13120/16963)	👎 -0.029
Conditionals	100.0% (0/0)	💚