Adjust curl retry and connection timeout handling

[edmorley]

In the shimmed CNBs used in heroku/builder we have been seeing quite a few transient errors related to buildpacks downloading from S3.

Adding appropriate retries and connection timeouts to all of our buildpack's curl usages should help with these, as well as make builds more reliable in general for users on Heroku, plus also anyone using a shimmed CNB locally with Pack CLI (where the network connection may be even less reliable).

The --retry-connrefused option has been used since otherwise curl doesn't retry cases where the connection was refused. Ideally we would use --retry-all-errors which takes that one step further, however that option was only added in curl 7.71, so is only supported by Heroku-22+.

For more on curl options, see:
https://curl.se/docs/manpage.html

GUS-W-11283397.

[kqiang]

@edmorley
--retry-connrefused is only available on the newer curl version. My code is impacted by this change because my curl version is 7.35.0. Could you do a curl version check before applying --retry-connrefused. ie.
if curl_version < XXX
do the old way
else
do the new way

[edmorley]

@kqiang Hi! --retry-connrefused is supported in curl 7.52+, which is therefore supported by Ubuntu 18.04+ and so all current Heroku stack versions. If you are using this buildpack with an older (and thus unsupported) operating system, you will need to pin to an older buildpack version. You are also likely at risk of security issues, if you are using old/unsupported Linux versions.