fix: improve dashboard loading performances (#7604)

Generating dashboard page takes too long when table `action` contains
many records and error log contains message like

```
2025/04/21 21:21:07 ...activities/action.go:470:GetFeeds() [W] [Slow SQL Query] SELECT `action`.* FROM `action` INNER JOIN `repository` ON `repository`.id = `action`.repo_id WHERE user_id=? AND is_deleted=? ORDER BY `action`.`created_unix` DESC LIMIT 20 [12 false] - 2m8.393454675s
```

This mod removes unnecessary inner join like proposed
in https://github.com/go-gitea/gitea/pull/32127

For complete solution index(user_id, is_deleted) for action table
should be created also like in https://github.com/go-gitea/gitea/pull/32333
(not included in this mod).

Related: https://github.com/go-gitea/gitea/pull/32127
Related: https://github.com/go-gitea/gitea/pull/32333
Author-Change-Id: IB#1160173

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### Tests

- I added test coverage for Go changes...
  - [x] in their respective `*_test.go` for unit tests.
  - [ ] in the `tests/integration` directory if it involves interactions with a live Forgejo server.
- I added test coverage for JavaScript changes...
  - [ ] in `web_src/js/*.test.js` if it can be unit tested.
  - [ ] in `tests/e2e/*.test.e2e.js` if it requires interactions with a live Forgejo server (see also the [developer guide for JavaScript testing](https://codeberg.org/forgejo/forgejo/src/branch/forgejo/tests/e2e/README.md#end-to-end-tests)).

### Documentation

- [ ] I created a pull request [to the documentation](https://codeberg.org/forgejo/docs) to explain to Forgejo users how to use this change.
- [x] I did not document these changes and I do not expect someone else to do it.

### Release notes

- [ ] I do not want this change to show in the release notes.
- [ ] I want the title to show in the release notes with a link to this pull request.
- [ ] I want the content of the `release-notes/<pull request number>.md` to be be used for the release notes instead of the title.

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/7604
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: Paweł Bogusławski <pboguslawski@noreply.codeberg.org>
Co-committed-by: Paweł Bogusławski <pboguslawski@noreply.codeberg.org>

models/activities/action.go

@@ -467,11 +467,8 @@ func GetFeeds(ctx context.Context, opts GetFeedsOptions) (ActionList, int64, err
 		return nil, 0, err
 	}
 
-	sess := db.GetEngine(ctx).Where(cond).
-		Select("`action`.*"). // this line will avoid select other joined table's columns
-		Join("INNER", "repository", "`repository`.id = `action`.repo_id")
-
 	opts.SetDefaultValues()
+	sess := db.GetEngine(ctx).Where(cond)
 	sess = db.SetSessionPagination(sess, &opts)
 
 	actions := make([]*Action, 0, opts.PageSize)

models/activities/action_test.go

@@ -226,24 +226,6 @@ func TestNotifyWatchers(t *testing.T) {
 	})
 }
 
-func TestGetFeedsCorrupted(t *testing.T) {
-	require.NoError(t, unittest.PrepareTestDatabase())
-	user := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
-	unittest.AssertExistsAndLoadBean(t, &activities_model.Action{
-		ID:     8,
-		RepoID: 1700,
-	})
-
-	actions, count, err := activities_model.GetFeeds(db.DefaultContext, activities_model.GetFeedsOptions{
-		RequestedUser:  user,
-		Actor:          user,
-		IncludePrivate: true,
-	})
-	require.NoError(t, err)
-	assert.Empty(t, actions)
-	assert.Equal(t, int64(0), count)
-}
-
 func TestConsistencyUpdateAction(t *testing.T) {
 	if !setting.Database.Type.IsSQLite3() {
 		t.Skip("Test is only for SQLite database.")

models/fixtures/action.yml

@@ -59,14 +59,6 @@
   created_unix: 1603011540 # grouped with id:7
 
 - id: 8
-  user_id: 1
-  op_type: 12 # close issue
-  act_user_id: 1
-  repo_id: 1700 # dangling intentional
-  is_private: false
-  created_unix: 1603011541
-
-- id: 9
   user_id: 34
   op_type: 12 # close issue
   act_user_id: 34