Subtract with Timezone bug

I experienced subtract error when I use timezones, an example:

```
import dayjs from 'dayjs';
import utc from 'dayjs/plugin/utc.js'
import timezone from 'dayjs/plugin/timezone.js'

dayjs.extend(utc);
dayjs.extend(timezone);

const dt1=dayjs().tz("Atlantic/Reykjavik")
console.log(dt1.format("YYYY-MM-DD HH:mm"))

const dt2=dt1.subtract(1,"day")
console.log(dt2.format("YYYY-MM-DD HH:mm"))
```

Result:

```
2023-08-24 00:38
2023-08-22 22:38
```

Version: "dayjs": "^1.11.7",

Start by running the provided reproduction with the utc and timezone plugin entry points, then inspect how subtract handles a timezone-aware Day.js value. Done means the one-day subtraction preserves the intended local time and produces the expected date for Atlantic/Reykjavik, with a regression test for the example.

Written by the indexing model from the issue text.