fix(Dr. Rai Reports): Allow ContactOverduePatientsIndicator for regions with data (#5695)

**Story card:**
[sc-16738](https://app.shortcut.com/simpledotorg/story/16738)

## Because

With regions which do not have dashboard data for `overdue_patients` and
/ or `contactable_overdue_patients`, the contact overdue patients
indicator breaks. Rightly so, because the data is missing.

## This addresses

Modifying the indicator to be unavailable when there is on data.

## Test instructions

suite tests

Author: igbanam

app/models/dr_rai/contact_overdue_patients_indicator.rb

@@ -37,7 +37,7 @@ def action_active
     end
 
     def is_supported?(region)
-      true
+      !datasource(region).empty?
     end
   end
 end

spec/models/dr_rai/contact_overdue_patients_indicator_spec.rb

@@ -1,6 +1,32 @@
 require "rails_helper"
 
 RSpec.describe DrRai::ContactOverduePatientsIndicator, type: :model do
+  describe "#is_supported?" do
+    let(:district_with_facilities) { setup_district_with_facilities }
+    let(:region) { district_with_facilities[:region] }
+    let(:indicator) { DrRai::ContactOverduePatientsIndicator.new }
+
+    context "when region has data" do
+      before do
+        allow(indicator).to receive(:datasource).with(region).and_return({"some" => "data"})
+      end
+
+      it "works" do
+        expect(indicator.is_supported?(region)).to be_truthy
+      end
+    end
+
+    context "when region has no data" do
+      before do
+        allow(indicator).to receive(:datasource).with(region).and_return({})
+      end
+
+      it "is unsupported" do
+        expect(indicator.is_supported?(region)).to be_falsey
+      end
+    end
+  end
+
   describe "indicator_function" do
     around do |example|
       Timecop.freeze("June 25 2025 15:12 GMT") { example.run }