urllib3 1.x used to accept socket._GLOBAL_DEFAULT_TIMEOUT as a sentinal
object to mean "no configured timeout".
In urllib3 2.x, urllib3 uses its own _DEFAULT_TIMEOUT sentinal object,
and it rejects socket._GLOBAL_DEFAULT_TIMEOUT.
Assign our own DEFAULT_TIMEOUT constant to the newer object if it
exists, and fall back to the old behavior on old urllib3 versions.
Co-authored-by: Vsevolod Fedorov <vsevolod.fedorov@gmail.com>
Closes-Bug: #2018567
Change-Id: Ic626ba0e8ed79eec3a63ffab6cc02f91aa545ab1
ba9f06e0c2