ORIGINAL SUMMARY: Investigate changes in SERVER-76698: Disable Curl Connection Pooling for STS requests

Disables the HTTP connection pooling for making requests to AWS STS by default. It can be re-enabled by setting a boolean setParameter awsSTSUseConnectionPool=trues.

Note: Docs - AWS IAM support in server is not publicly documented so this ticket may be not require any docs work.

Description of Linked Ticket

Disable Curl Connection pooling since it is appears to be a source of errors in several customer issues. Connections are made from mongod/mongos, go idle, are likely cut by the result side (impossible to know without network captures) and then auth fails.

By disabling connection pooling, we reduce the complexity in this coe.