Fix repository settings form template to work with redmine 4.x

[mathprod]

Patch from comments in issue #742
(#742 (comment))

[PowerKiKi]

Did anybody manually tested this latest patch version ?

[mathprod]

Thank for merging this.
About the previous question: this patch was tested on the following setup (Debian10)

Environment:
  Redmine version                4.1.1.stable
  Ruby version                   2.5.5-p157 (2019-03-15) [arm-linux-gnueabihf]
  Rails version                  5.2.4.2
  Environment                    production
  Database adapter               Mysql2
  Mailer queue                   ActiveJob::QueueAdapters::AsyncAdapter
  Mailer delivery                smtp
SCM:
  Subversion                     1.10.4
  Git                            2.20.1
  Filesystem                     
  Xitolite                       2.20.1
Redmine plugins:
  additionals                    2.0.23
  redmine_bootstrap_kit          0.2.5
  redmine_code_review            1.0.0
  redmine_default_members        1.0-devel
  redmine_dmsf                   2.4.2 devel
  redmine_embedded               0.0.2
  redmine_git_hosting            4.0.1
  redmine_per_project_formatting 0.1.0