[tagger] Extract list of tags to its own package

[davidor]

What does this PR do?

This PR is a refactor. No changes in functionality.

This PR extracts the list of tags handled by the tagger to its own package. This has a few advantages:

• To know if a tag is added by the tagger or not now we just need to look at the list in the new file added in this PR.
• Other projects will be able to use the constants defined instead of having to redeclare them. This was asked by the otel team.
• Remove some duplication because some tags were defined in multiple places.

This PR is easier to review commit by commit.

Describe how to test/QA your changes

Skip. This should be covered by e2e and unit tests.

[pr-commenter]

Test changes on VM

Use this command from test-infra-definitions to manually test this PR changes on a VM:

inv create-vm --pipeline-id=37098659 --os-family=ubuntu

Note: This applies to commit be81afb

[davidor]

/merge

[dd-devflow]

🚂 MergeQueue: pull request added to the queue

The median merge time in main is 30m.

Use /merge -c to cancel this operation!