MONTHS_IN_FORMAT is wrong in locales with ordinals

**Describe the bug**
In Russian locale (maybe in others too) when using "Do" format [months](https://github.com/iamkun/dayjs/blob/9c20e77caf7b1b5eccf418175203b198d4e29535/src/locale/ru.js#L30) function working incorrectly.
For example:
`dayjs().locale("ru").format("Do MMMM")`
will output "21 март" but correct one is "21 марта".
That's because "format" argument in [months](https://github.com/iamkun/dayjs/blob/9c20e77caf7b1b5eccf418175203b198d4e29535/src/locale/ru.js#L30) function is "21 MMMM" instead of "Do MMMM" and therefore the MONTHS_IN_FORMAT regex does not work properly..
I have not found a reason why ordinal replaced before locale.

**Information**
- Day.js Version [e.g. v1.10.4]

Start with the months function in src/locale/ru.js and trace how format handles the Do MMMM example before that locale function receives its format argument. The fix is complete when dayjs().locale("ru").format("Do MMMM") produces the correct genitive month form, such as "21 марта", with regression coverage added in the relevant formatting tests.

Written by the indexing model from the issue text.