[web] Remove SubscriptionFormatters, format subscription dates in the frontend (#36409)

* [web] Remove SubscriptionFormatters, format subscription dates in the frontend

Replace the server-formatted nextPaymentDueAt/nextPaymentDueDate/
trialEndsAtFormatted fields with the raw periodEnd date and format in
the React dashboard (same strings as before, English + UTC). Also
consolidate hand-rolled trial checks onto isInFreeTrial /
SubscriptionHelper.isInTrial.

* [web] Remove the now-unused dateformat dependency

* [web] Address review: payment-dates unit test, UTC dates in acceptance test

Add a dedicated unit test asserting the exact formatted strings from
formatPaymentDate/formatPaymentDateTime, and use explicit UTC timestamps
in the SubscriptionDashboard acceptance fixtures instead of
local-timezone Date constructors.

GitOrigin-RevId: 16ac4f1098b14ef9f1478d22cf39c1357ead7dea

services/web/test/frontend/features/subscription/util/is-in-free-trial.test.ts

@@ -1,6 +1,5 @@
 import { expect } from 'chai'
 import isInFreeTrial from '../../../../../frontend/js/features/subscription/util/is-in-free-trial'
-import dateformat from 'dateformat'
 
 describe('isInFreeTrial', function () {
   it('returns false when no date sent', function () {
@@ -15,10 +14,6 @@ describe('isInFreeTrial', function () {
   it('returns true when date is in the future', function () {
     const today = new Date()
     const sevenDaysFromToday = new Date().setDate(today.getDate() + 7)
-    const sevenDaysFromTodayFormatted = dateformat(
-      sevenDaysFromToday,
-      'dS mmmm yyyy'
-    )
-    expect(isInFreeTrial(sevenDaysFromTodayFormatted)).to.be.true
+    expect(isInFreeTrial(new Date(sevenDaysFromToday).toISOString())).to.be.true
   })
 })

services/web/test/frontend/features/subscription/util/payment-dates.test.ts

@@ -0,0 +1,31 @@
+import { expect } from 'chai'
+import {
+  formatPaymentDate,
+  formatPaymentDateTime,
+} from '../../../../../frontend/js/features/subscription/util/payment-dates'
+
+describe('payment-dates', function () {
+  describe('formatPaymentDate', function () {
+    it('formats a date in UTC', function () {
+      expect(formatPaymentDate('2025-02-20T12:00:00.000Z')).to.equal(
+        'February 20th, 2025'
+      )
+    })
+    it('returns null for missing dates', function () {
+      expect(formatPaymentDate(null)).to.be.null
+      expect(formatPaymentDate(undefined)).to.be.null
+    })
+  })
+
+  describe('formatPaymentDateTime', function () {
+    it('formats a date and time in UTC', function () {
+      expect(formatPaymentDateTime('2025-02-20T12:00:00.000Z')).to.equal(
+        'February 20th, 2025 12:00 PM UTC'
+      )
+    })
+    it('returns null for missing dates', function () {
+      expect(formatPaymentDateTime(null)).to.be.null
+      expect(formatPaymentDateTime(undefined)).to.be.null
+    })
+  })
+})