In a similar vein to OSGeo#4302, remove deprecated implementation
of db_set_login() and replace it with that of db_set_login2().

Along with db_get_login(), db_set_login() was deprecated
(in favour of db_set_login2) in 2015 with the 7.8.0 release.
Commit: da399c5

Signed-off-by: Mohan Yelugoti <ymdatta.work@gmail.com>

db_set_login() is deprecated in 7.8.0 release with da399c5.
Change its function signature and implementation to match that
of currently preferred db_set_login2().

Modify db_set_login2() to internally call db_set_login()
function call. In the future major version, db_set_login() would
be removed to have only one method to set login details for
simplicity.

Signed-off-by: Mohan Yelugoti <ymdatta.work@gmail.com>

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>