Fixes multiple issues with retry function in rhel-registration.

Fixes multiple issues with retry function in rhel-registration.

There were multiple issues in retry() in rhel-registration:
 - There was no need for it to be recursive (local variables
   got overwritten)
 - There was no delay between multiple attempts, leading to faster but
   more frequent failures.
 - The max number of attempts was set too low for some environements.

With this patch, rhel-registration now works more reliably with slow-links
for portal registration and does not attempt to DDos the portal or your
satellite server.

Closes-Bug: #1674358
Change-Id: I594d3c94867b45a7a58766dbcc66edead78d6a4e
(cherry picked from commit 038eae089130bc3a814897c0e282223de16f4658)