ldap: Move ZulipLDAPAuthBackendBase.get_or_build_user definition.
ldap: Move ZulipLDAPAuthBackendBase.get_or_build_user definition.

This function is inherited by ZulipLDAPUserPopulator and overriden by
ZulipLDAPAuthBackend, so it's more clear to have it simply defined in
ZulipLDAPUserPopulator directly.

zulip/zulip,zulip/zulip,eeshangarg/zulip,hackerkid/zulip,andersk/zulip,andersk/zulip,kou/zulip,brainwane/zulip,showell/zulip,synicalsyntax/zulip,synicalsyntax/zulip,andersk/zulip,zulip/zulip,hackerkid/zulip,showell/zulip,brainwane/zulip,eeshangarg/zulip,kou/zulip,timabbott/zulip,zulip/zulip,brainwane/zulip,andersk/zulip,zulip/zulip,rht/zulip,shubhamdhama/zulip,kou/zulip,synicalsyntax/zulip,shubhamdhama/zulip,zulip/zulip,andersk/zulip,rht/zulip,synicalsyntax/zulip,rht/zulip,hackerkid/zulip,timabbott/zulip,kou/zulip,showell/zulip,timabbott/zulip,eeshangarg/zulip,kou/zulip,punchagan/zulip,brainwane/zulip,hackerkid/zulip,punchagan/zulip,timabbott/zulip,shubhamdhama/zulip,shubhamdhama/zulip,eeshangarg/zulip,andersk/zulip,brainwane/zulip,kou/zulip,eeshangarg/zulip,showell/zulip,eeshangarg/zulip,andersk/zulip,synicalsyntax/zulip,hackerkid/zulip,shubhamdhama/zulip,hackerkid/zulip,rht/zulip,punchagan/zulip,rht/zulip,synicalsyntax/zulip,punchagan/zulip,punchagan/zulip,showell/zulip,brainwane/zulip,timabbott/zulip,shubhamdhama/zulip,kou/zulip,timabbott/zulip,zulip/zulip,eeshangarg/zulip,timabbott/zulip,showell/zulip,shubhamdhama/zulip,synicalsyntax/zulip,rht/zulip,brainwane/zulip,punchagan/zulip,rht/zulip,showell/zulip,punchagan/zulip,hackerkid/zulip