v2/contrib: update contrib naming policy

[darccio]

What does this PR do?

Contrib naming policy has been changed. The previous one, if applied consistently, would lead to a bigger number of breaking changes.

The new one provides a better balance between our current existing contribs and having a consistent way to know from the import URL - combining it with the current version of the integrated package - what versions are supported in the integration.

The current contribs have been updated according to the new policy:

• IBM/sarama.v1: renamed to IBM/sarama (only v1 is available)
• olivere/elastic: renamed to olivere/elastic.v5 (the minimum supported version is v5,gopkg.in/olivere/elastic.v5)
• segmentio/kafka.go.v0: renamed to segmentio/kafka-go (only v0 available, suffix not needed).
• valyala/fasthttp.v1: renamed to valyala/fasthttp (only v1 is available).

The rest of integrations don’t need any change, as:

• their integrated packages have only a v0 version
• or they are compatible with v0 and any other major version
• or they are already in the minimum supported major version
• or their v0 was not published as a module
• or they manage their package in a way that any lower major version has a version suffix but the current one not (like github.com/twitch/twirp).

Test methodology: downgrade the integrated packages to their highest v0 version and run go test -v ./.... Code must compile and tests must pass.

Motivation

Fix #544

Reviewer's Checklist

• Changed code has unit tests for its functionality at or near 100% coverage.
• System-Tests covering this feature have been added and enabled with the va.b.c-dev version tag.
• There is a benchmark for any new code, or changes to existing code.
• If this interacts with the agent in a new way, a system test has been added.
• Add an appropriate team label so this PR gets put in the right place for the release notes.
• Non-trivial go.mod changes, e.g. adding new modules, are reviewed by @DataDog/dd-trace-go-guild.

For Datadog employees:

• If this PR touches code that handles credentials of any kind, such as Datadog API keys, I've requested a review from @DataDog/security-design-and-guidance.
• This PR doesn't touch any of that.

Unsure? Have a question? Request a review!

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-02-23 14:38:10

Comparing candidate commit 2b19a23 in PR branch dario.castane/AIT-8732/contrib-naming-policy with baseline commit 0206562 in branch v2-dev.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 39 metrics, 2 unstable metrics.

[rarguelloF]

The new naming policy LGTM!