`TestResourceRefsGetResourceGo` is flaky about pulumi

[Frassle]

Got a slightly different stack trace:

panic: expected message "hello world!" not equal to actual message ""
    goroutine 45 [running]:
    main.main.func1.1(***0xc000171230?, 0x2?, 0x0?***)
    	/home/runner/go/src/stackName-1721331326864178436-827910/main.go:138 +0x16e
    reflect.Value.call(***0xcf58e0?, 0xee06b8?, 0x30?***, ***0xe744e7, 0x4***, ***0xc000600bd0, 0x1, 0xc000526878?***)
    	/opt/hostedtoolcache/go/1.22.5/x64/src/reflect/value.go:596 +0xca6
    reflect.Value.Call(***0xcf58e0?, 0xee06b8?, 0x101000000000000?***, ***0xc000600bd0?, 0x0?, 0x3?***)
    	/opt/hostedtoolcache/go/1.22.5/x64/src/reflect/value.go:380 +0xb9
    github.com/pulumi/pulumi/sdk/v3/go/internal.(*applier).Call(0xc000529940, ***0xfcf570, 0x17480c0***, ***0xca67a0?, 0xc0004bc570?, 0x0?***)
    	/home/runner/work/pulumi/pulumi/sdk/go/internal/types.go:510 +0x22d
    github.com/pulumi/pulumi/sdk/v3/go/internal.(*OutputState).applyTWithApplier.func1()
    	/home/runner/work/pulumi/pulumi/sdk/go/internal/types.go:622 +0x16a
    created by github.com/pulumi/pulumi/sdk/v3/go/internal.(*OutputState).applyTWithApplier in goroutine 1
    	/home/runner/work/pulumi/pulumi/sdk/go/internal/types.go:609 +0x265

[tgummerer]

I just realized the NodeJS version of this test is flaky as well (#11677), probably for the same reasons.

The problem here is that RegisterResourceOutputs is run in a Goroutine/async in NodeJS. This means the registration of the resource output might not complete before we try to access the child resource. But because of how resource registration works, we might already have registered a nil value for that field. Thus the UnsafeAwait/pulumi.All don't wait any longer, because the RegisterResourceOutputs might not even have started at this point.

This can easily be reproduced using the following diff:

diff --git a/sdk/go/pulumi/context.go b/sdk/go/pulumi/context.go
index e4a75dd7b8..f15b276e5b 100644
--- a/sdk/go/pulumi/context.go
+++ b/sdk/go/pulumi/context.go
@@ -29,6 +29,7 @@ import (
        "sort"
        "strings"
        "sync"
+       "time"
 
        multierror "github.com/hashicorp/go-multierror"
        "github.com/pulumi/pulumi/sdk/v3/go/common/resource"
@@ -2191,6 +2195,7 @@ func (ctx *Context) RegisterResourceOutputs(resource Resource, outs Map) error {
        }
 
        go func() {
+               time.Sleep(5 * time.Second)
                // No matter the outcome, make sure all promises are resolved and that we've signaled completion of this RPC.
                var err error
                defer func() {