With `experimental_build_compiler_from_source`, output includes misleading instructions

```
Installed Go for linux/amd64 in /buildbuddy-execroot/_bootstrap_sdk_workdir_18222_10088/goroot
Installed commands in /buildbuddy-execroot/_bootstrap_sdk_workdir_18222_10088/goroot/bin
*** You need to add /buildbuddy-execroot/_bootstrap_sdk_workdir_18222_10088/goroot/bin to your PATH.
[954 / 3,988] Bootstrapping Go SDK from source [for tool]; 99s remote, disk-cache, remote-cache ... (3 actions running)
INFO: From Bootstrapping Go SDK from source [for tool]:
Building Go cmd/dist using /buildbuddy-execroot/external/rules_go++go_sdk+go_sdk. (go1.26.0 linux/amd64)
Building Go toolchain1 using /buildbuddy-execroot/external/rules_go++go_sdk+go_sdk.
Building Go bootstrap cmd/go (go_bootstrap) using Go toolchain1.
Building Go toolchain2 using go_bootstrap and Go toolchain1.
Building Go toolchain3 using go_bootstrap and Go toolchain2.
Building packages and commands for linux/amd64.
```

appears during the Bazel build when bootstrapping the compiler. But the user does not need to and in fact should not "add /buildbuddy-execroot/_bootstrap_sdk_workdir_18222_10088/goroot/bin to your PATH". Is there a way to silence this output by default?

Reproduce a Bazel build using `experimental_build_compiler_from_source` and trace where the bootstrap output is emitted. Check the surrounding rules_go build and test coverage, then ensure the misleading PATH instruction is silent by default without hiding the useful compiler-bootstrap messages.

Written by the indexing model from the issue text.