go-unit-tests: TestSendAdmissionReleasesWhenCallEndsBeforeExecution flakes (reply_returns_its_task_to_waiting) #332

Problem

go-unit-tests failed on #329 (three markdown files under fork/carried/, no Go change) in go/adk/pkg/taskstore: TestSendAdmissionReleasesWhenCallEndsBeforeExecution/reply_returns_its_task_to_waiting — executor_test.go:386: "Condition never satisfied: the superseded send must reach a boundary without native work" after 5.01 s, while the sibling new_task_is_canceled passed in 0.03 s. Run: https://github.com/giantswarm/kagent-upstream/actions/runs/37971632164 (job 113959442825). The same package passed on #330 (the same kind of change) and on the giantswarm branch at f2cd87e.

The log shows ERROR settle runtime task boundary … error="read runtime identity: open : no such file or directory" twice right before the wait, from the two sends the subtest starts.

Proposed solution

Find what keeps the superseded send from reaching its boundary within the Eventually window when the runtime identity file is absent (the settle error above), and make the test wait on the boundary event itself or give the executor what it needs to settle; until then the check is red on a flake and blocks merges into giantswarm.

Acceptance criteria

• The subtest passes on ten consecutive go test -count=10 ./go/adk/pkg/taskstore/... runs.
• go-unit-tests is green on a pull request that changes no Go file.