Tracing: Docs and config improvements for Tempo/Jaeger/Zipkin

[joey-grafana]

What is this feature?

Improves the docs for Tempo, Jaeger & Zipkin.

Why do we need this feature?

Makes how to use and configure these data sources clearer. Updates provisioning examples, terminology and descriptive text.

Who is this feature for?

Anyone who uses the Tempo, Jaeger or Zipkin data sources.

Which issue(s) does this PR fix?:

Fixes #64659

Special notes for your reviewer:

Please check that:

• It works as expected from a user's perspective.
• If this is a pre-GA feature, it is behind a feature toggle.
• The docs are updated, and if this is a notable improvement, it's added to our What's New doc.
• There are no known compatibility issues with older supported versions of Grafana, or plugins.
• It passes the Hosted Grafana feature readiness review for observability, scalability, performance, and security.

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[github-actions]

Backend code coverage report for PR #65255
No changes

[github-actions]

Frontend code coverage report for PR #65255

Plugin	Main	PR	Difference
explore	86.48%	86.48%	0%

[knylander-grafana]

Thank you for adding documentation! Approving the changes, with some minor suggestions.

[chri2547]

@joey-grafana , after you've accepted @knylander-grafana suggestions, hit me up directly to merge this for you (if you are unable to merge yourself). Thanks for the great work!