fix(tests): pin Go e2e test app to 1.26.1 for eBPF offset compatibility

[frzifus]

Summary

• Pins the Go e2e test app base image to golang:1.26.1-alpine instead of the floating 1.26-alpine tag
• The Go auto-instrumentation (v0.24.0) only has cached eBPF offsets up to Go 1.26.1. The recent Go 1.26 upgrade (chore: update Go to 1.26 #5173) resolved to Go 1.26.3 via the floating tag, causing instrumentation-go e2e tests to fail with no telemetry data produced
• Once a new opentelemetry-go-instrumentation release adds offsets for Go 1.26.3+, this pin can be removed

See: https://github.com/open-telemetry/opentelemetry-go-instrumentation/releases/

Test plan

• e2e-instrumentation CI job passes (specifically instrumentation-go test)

[github-actions]

E2E Test Results

 37 files  214 suites   2h 6m 35s ⏱️
101 tests  98 ✅ 1 💤 2 ❌
235 runs  229 ✅ 2 💤 4 ❌

Results for commit 2aa74a5.

♻️ This comment has been updated with latest results.

[swiatekm]

Doesn't look like this is fixing the failures. Maybe we should revert the Go test app change until we figure this out?

[iblancasa]

Doesn't look like this is fixing the failures. Maybe we should revert the Go test app change until we figure this out?

I think we should deprecate Go instrumentation #4539

[swiatekm]

Doesn't look like this is fixing the failures. Maybe we should revert the Go test app change until we figure this out?

I think we should deprecate Go instrumentation #4539

That, too, but first we need to unblock our CI in the simplest possible change.

[frzifus]

Doesn't look like this is fixing the failures. Maybe we should revert the Go test app change until we figure this out?

I think we should deprecate Go instrumentation #4539

That, too, but first we need to unblock our CI in the simplest possible change.

@iblancasa @swiatekm In any case I think we have to force merge something. 😓

[swiatekm]

Doesn't look like this is fixing the failures. Maybe we should revert the Go test app change until we figure this out?

I think we should deprecate Go instrumentation #4539

That, too, but first we need to unblock our CI in the simplest possible change.

@iblancasa @swiatekm In any case I think we have to force merge something. 😓

I don't think we do? The Go 1.26.4 update PR passes govulncheck. We just need to disable the Go e2e test there. Let me have a stab at it.

[swiatekm]

@frzifus can you build this locally and sure it passes e2e tests?