DEPR: deprecate Index.holds_integer
See https://github.com/pandas-dev/pandas/issues/50042#issuecomment-1349283717

Ok, I understand. I'll look into it tomorrow. I've never worked on this part of the code base, hopefully it's not too complex. @jbrockmendel , any comment? The ARM failure looks unrelated. I've changed this to use `Index._holds_integer`. Ping. 👍 . I've updated this PR after it was decided that it is ok now to merge deprecation PRs.

The code checks errors are unrelated to this PR. I’ve rerun the failed tests and everything is green now. thx @topper-123 