Remove Select2v4.0.6rc1 dropdown workaround when possible

[gorj-tessella]

As of Select2 v4.0.6rc1 (and previous v4 versions) there is odd behavior around clicking the "unselect" x button. Instead of just removing the item in a multiselect, or clearing the selection of a select, it also opens the dropdown. This behavior was not present in 3.5.3, and has been documented since 2015 (select2/select2#3320). Despite being raised many times along with some pull requests, it has not been addressed and given the rate of work on select2 may not be for some time. While annoying, it is not a dealbreaker and hopefully will be addressed at some point. Currently the code has a workaround.