Fix missing outputs for jobs with matrix (#32823)

Fix #32795

If a job uses a matrix, multiple `ActionRunJobs` may have the same
`JobID`. We need to merge the outputs of these jobs to make them
available to the jobs that need them.

(cherry picked from commit 7269130d2878d51dcdf11f7081a591f85bd493e8)

Conflicts:
	models/fixtures/action_run.yml
	models/fixtures/action_run_job.yml
  trivial context conflicts

routers/api/actions/runner/utils_test.go

@@ -0,0 +1,29 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package runner
+
+import (
+	"context"
+	"testing"
+
+	actions_model "code.gitea.io/gitea/models/actions"
+	"code.gitea.io/gitea/models/unittest"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_findTaskNeeds(t *testing.T) {
+	require.NoError(t, unittest.PrepareTestDatabase())
+
+	task := unittest.AssertExistsAndLoadBean(t, &actions_model.ActionTask{ID: 51})
+
+	ret, err := findTaskNeeds(context.Background(), task)
+	require.NoError(t, err)
+	assert.Len(t, ret, 1)
+	assert.Contains(t, ret, "job1")
+	assert.Len(t, ret["job1"].Outputs, 2)
+	assert.Equal(t, "abc", ret["job1"].Outputs["output_a"])
+	assert.Equal(t, "bbb", ret["job1"].Outputs["output_b"])
+}