[3.12] gh-112064: Fix incorrect handling of negative read sizes in `HTTPResponse.read()` (GH-128270) (#129396)

gh-112064: Fix incorrect handling of negative read sizes in `HTTPResponse.read()` (GH-128270)

The parameter `amt` of `HTTPResponse.read()`, which could be a negative integer,
has not been handled before and led to waiting for the connection to close
for `keep-alive connections`. Now, this has been fixed, and passing negative values
to `HTTPResponse().read()` works the same as passing `None` value.
(cherry picked from commit 4d0d24f6e3dff2864007c3cfd1cf7d49c6ee5317)

Co-authored-by: Yury Manushkin <manushkin@gmail.com>