[exporter/datadog] Deprecate service and version settings

[mx-psi]

Description:

Deprecate service and version settings in favor of using the service.name and service.version semantic conventions respectively.

Link to tracking Issue: #8781 and #8783

Testing: Tested that deprecation warnings are logged when using these settings.

Documentation: Removed service and version from examples.

[KSerrania]

Left a question, otherwise LGTM.

[KSerrania]

We're deprecating these options, but they're technically still supported until v0.51.0. Should we keep the tests until we definitely remove these options (to prevent breaking the behavior of these options before the scheduled date)?

[mx-psi]

I added back this with a comment stating they are deprecated. I didn't do this originally because you need to check Config fields individually until we do #8373 (since the warnings field is unexported)

[codeboten]

Please resolve conflicts

[mx-psi]

Done!

[mx-psi]

@codeboten could this be merged if it looks good? I fixed the conflicts

[codeboten]

Sorry @mx-psi, I missed this message and it looks like there are more conflicts to resolve :(

[mx-psi]

Should be good now :)

[jpkrohling]

There's a release in progress, so I shouldn't merge this. After the release, this PR will likely get outdated (changelog, go.mod/sum).

[mx-psi]

Alright, will remove the 'ready to merge' label then until after v0.48.0 is done

[mx-psi]

v0.48.0 is done, so I merged main into this branch, updated the CHANGELOG and marked as ready to merge