Add instruction how to update Go version for macrobenchmarks

[ddyurchenko]

What does this PR do?

1. Adds instruction how to update Go version for macrobenchmarks.
2. Adds retries for macrobenchmarks that failed due to internal Gitlab errors (which are expected to happen 1 in ca. 900 runs on avg).

Motivation

Go macrobenchmarks were broken since last Thursday due to e8dc974, because Docker image was not updated with newer Go versions.

I've already updated the image in background, so now the pipeline is fixed.

This PR adds more specific instructions on updating Go versions.

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.

Unsure? Have a question? Request a review!

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-07-17 16:51:18

Comparing candidate commit dc8b651 in PR branch ddyurchenko/add-version-update-disclaimer with baseline commit 0a6bcb7 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 47 metrics, 0 unstable metrics.

[nsrip-dd]

Thanks!