[aws][customer][ccoctl] Fix issue when installing STS from restricted networks (Proxy)

Goal:

• Track issue reported on Slack for a customer trying to install a private cluster on AWS with STS mode and private S3 bucket, from restricted networks (behind proxy)

Problem statement:

• ccoctl is failing when checking the public endpoint created

References:

•  [1] https://redhat-internal.slack.com/archives/CE3ETN3J8/p1703762408695639
•  [2] https://redhat-internal.slack.com/archives/C04TMSTHUHK/p1705632538052949
• [3] https://issues.redhat.com/browse/OCPBUGS-27214
•  [4] https://github.com/openshift/cloud-credential-operator/pull/654