Remove unused helper methods

They aren't used since commits a6585361, 3752f3a5, 88a7a29d, eef8ad1b,
f67f058b, 04910fea and 9181610d. The method `image_bytes_to_megabytes`
was never used and is a duplicate of the method `bytes_to_megabytes`.

app/controllers/concerns/dashboard/group_supports.rb

@@ -39,17 +39,6 @@ module Dashboard::GroupSupports
 
       complete_grouped_votes
     end
-
-    def previous_key_for(date)
-      grouping_key_for(date - interval)
-    end
-
-    def interval
-      return 1.week if params[:group_by] == "week"
-      return 1.month if params[:group_by] == "month"
-
-      1.day
-    end
   end
 
   private

app/helpers/application_helper.rb

@@ -1,12 +1,4 @@
 module ApplicationHelper
-  def home_page?
-    return false if user_signed_in?
-
-    # Using path because fullpath yields false negatives since it contains
-    # parameters too
-    request.path == "/"
-  end
-
   # if current path is /debates current_path_with_query_params(foo: "bar") returns /debates?foo=bar
   # notice: if query_params have a param which also exist in current path,
   # it "overrides" (query_params is merged last)

app/helpers/documents_helper.rb

@@ -11,10 +11,6 @@ module DocumentsHelper
     bytes / Numeric::MEGABYTE
   end
 
-  def document_nested_field_wrapper_id(index)
-    "document_#{index}"
-  end
-
   def render_destroy_document_link(builder, document)
     if !document.persisted? && document.cached_attachment.present?
       link_to t("documents.form.delete_button"),

app/helpers/imageables_helper.rb

@@ -3,10 +3,6 @@ module ImageablesHelper
     imageable.image.present? && can?(:destroy, imageable.image)
   end
 
-  def imageable_class(imageable)
-    imageable.class.name.parameterize(separator: "_")
-  end
-
   def imageable_max_file_size
     bytes_to_megabytes(Setting["uploads.images.max_size"].to_i.megabytes)
   end

app/helpers/images_helper.rb

@@ -17,10 +17,6 @@ module ImagesHelper
     image.errors[:attachment].join(", ") if image.errors.key?(:attachment)
   end
 
-  def image_bytes_to_megabytes(bytes)
-    bytes / Numeric::MEGABYTE
-  end
-
   def image_class(image)
     image.persisted? ? "persisted-image" : "cached-image"
   end

app/helpers/officers_helper.rb

@@ -1,8 +1,4 @@
 module OfficersHelper
-  def officer_label(officer)
-    truncate([officer.name, officer.email].compact.join(" - "), length: 100)
-  end
-
   def vote_collection_shift?
     current_user.poll_officer.officer_assignments.voting_days.where(date: Time.current.to_date).any?
   end

app/helpers/polls_helper.rb

@@ -19,22 +19,6 @@ module PollsHelper
     end
   end
 
-  def poll_dates_select_options(poll)
-    options = []
-    (poll.starts_at.to_date..poll.ends_at.to_date).each do |date|
-      options << [l(date, format: :long), l(date)]
-    end
-    options_for_select(options, params[:d])
-  end
-
-  def poll_booths_select_options(poll)
-    options = []
-    poll.booths.each do |booth|
-      options << [booth_name_with_location(booth), booth.id]
-    end
-    options_for_select(options)
-  end
-
   def booth_name_with_location(booth)
     location = booth.location.blank? ? "" : " (#{booth.location})"
     booth.name + location