optimize lazy collectAll implement

### Search before asking

- [ ] I searched the [issues](https://github.com/alibaba/async_simple/issues) and found no similar issues.

### What happened + What you expected to happen

https://github.com/alibaba/async_simple/blob/ab70389831cb2b9be060fd66c913833c000843fc/async_simple/coro/Collect.h#L229

```c++
Lazy<> foo() {}

collectAll(foo().via(executor)) is equal to collectAllPara(foo())
```

maybe we can use collectAll(foo().via(executor)) to simplify the collectAllPara, for example: collectAllPara call collectAll(foo().via(executor)) directly

### Reproduction way

### Anything else

### Are you willing to submit a PR?

- [ ] Yes I am willing to submit a PR!

Start with async_simple/coro/Collect.h around line 229 and compare the behavior of collectAll(foo().via(executor)) with collectAllPara(foo()). Trace how collectAllPara currently delegates or schedules work. Done means the implementation is simplified as proposed without changing the observable collection behavior; the payload does not name a test file to run.

Written by the indexing model from the issue text.