Cache LDAP attributes to go easy on memory footprint. Where I saw this...

Cache LDAP attributes to go easy on memory footprint. Where I saw this problem, each LDAP BasicAttributes is about 30K big, and a programmatic client logged in 7000 times, resulting in 140MB of memory consumption just by LDAP attributes.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@34211 71c3de6d-444a-0410-be80-ed276b4c234a