x/telemetry/config: add collection for gopls/gotoolchain

[findleyr]

Summary

In #65917, we plan to use forward compatibility to ensure that gopls is installed with the latest Go toolchain.
Before doing so, we want to understand what fraction of users work in an environment where toolchain upgrades are supported. By collecting the gopls/gotoolchain counter, we can help inform this understanding.

Proposed Config Change

https://go.dev/cl/603857

[gabyhelp]

Related Issues and Documentation

• x/tools/gopls: add telemetry counters that will help with the v0.17.0 release #68240 (closed)
• x/telemetry/config: temporarily allow gopls `devel` versions to upload telemetry data #62271 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[cagedmantis]

cc @golang/telemetry

[findleyr]

This was discussed in the telemetry meeting last week, with no objections. Since there have been no external objections, I'll accept and implement.

[gopherbot]

Change https://go.dev/cl/603857 mentions this issue: internal/chartconfig: add collection for gopls/gotoolchain