v0.22.0 is not built properly for arm64

[RonFed]

Following #1962, the Dockerfile was changed to run the generate and build command without using the Makefile. This cause the TARGETARCH env var to not get propagated to the go build command - hence the image was effictively built only for amd64.
Since our e2e test were changed to only run as go tests - this was not tested (since our k8s tests were removed).

Running the v0.22.0 image on arm results in:

{"time":"2025-06-02T11:18:54.487189595Z","level":"INFO","source":{"function":"main.(*ProcessPoller).Poll","file":"/usr/src/go.opentelemetry.io/auto/cli/process_poller.go","line":69},"msg":"Polling for process","binary":"/app/odigos-ui","interval":2000000000}
{"time":"2025-06-02T11:18:56.499045596Z","level":"INFO","source":{"function":"main.(*ProcessPoller).Poll","file":"/usr/src/go.opentelemetry.io/auto/cli/process_poller.go","line":92},"msg":"process found","PID":21}
{"time":"2025-06-02T11:18:56.500363554Z","level":"INFO","source":{"function":"main.main","file":"/usr/src/go.opentelemetry.io/auto/cli/main.go","line":138},"msg":"building OpenTelemetry Go instrumentation ...","version":{"Release":"v0.22.0","Revision":"unknown","Go":{"Version":"go1.24.3","OS":"linux","Arch":"amd64"}}}
{"time":"2025-06-02T11:18:56.512250846Z","level":"INFO","source":{"function":"main.main","file":"/usr/src/go.opentelemetry.io/auto/cli/main.go","line":161},"msg":"building OpenTelemetry Go instrumentation ...","PID":21,"version":{"Release":"v0.22.0","Revision":"unknown","Go":{"Version":"go1.24.3","OS":"linux","Arch":"amd64"}}}
{"time":"2025-06-02T11:18:56.561809971Z","level":"ERROR","source":{"function":"main.main","file":"/usr/src/go.opentelemetry.io/auto/cli/main.go","line":169},"msg":"failed to create instrumentation","error":"error while scanning instructions: failed to decode x64 instruction at offset 52: unrecognized instruction"}

[MrAlias]

I'm not following how #1962 changed the behavior of the TARGETARCH var. Prior to that PR the makefile did not set a default value either. As shown in the changed files the scope of setting GOARCH=$TARGETARCH didn't change.

How did #1962 cause the TARGETARCH value to not get propagated to the go build command?

[MrAlias]

How did #1962 cause the TARGETARCH value to not get propagated to the go build command?

$ go env GOARCH
amd64

$ GOARCH=arm64 go env GOARCH && go env GOARCH
arm64
amd64

https://github.com/open-telemetry/opentelemetry-go-instrumentation/pull/1962/files#diff-dd2c0eb6ea5cfc6c4bd4eac30934e2d5746747af48fef6da689e85b752f39557R24-R28