[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

yarn.lock

@@ -8006,7 +8006,6 @@ __metadata:
     "@types/bootstrap": "npm:^5.2.10"
     "@types/chai": "npm:^4.3.0"
     "@types/chai-as-promised": "npm:^8.0.2"
-    "@types/dateformat": "npm:^5.0.3"
     "@types/diff": "npm:^5.2.3"
     "@types/dom-speech-recognition": "npm:^0.0.7"
     "@types/events": "npm:^3.0.3"
@@ -8100,7 +8099,6 @@ __metadata:
     cypress-multi-reporters: "npm:^2.0.5"
     cypress-plugin-tab: "npm:^1.0.5"
     d3: "npm:^3.5.16"
-    dateformat: "npm:1.0.4-1.2.3"
     daterangepicker: "npm:2.1.27"
     diff: "npm:^5.1.0"
     dompurify: "npm:^3.3.2"
@@ -10795,13 +10793,6 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@types/dateformat@npm:^5.0.3":
-  version: 5.0.3
-  resolution: "@types/dateformat@npm:5.0.3"
-  checksum: 10c0/828452c096b0b6901a64ce1f3a47fb96755f2451a2605b59fb271407526c62020d171aab6946f9268ca5a4d63db7952c32595bf30b49ed54b218414ec6a02261
-  languageName: node
-  linkType: hard
-
 "@types/debug@npm:^4.0.0, @types/debug@npm:^4.1.12, @types/debug@npm:^4.1.8":
   version: 4.1.13
   resolution: "@types/debug@npm:4.1.13"
@@ -16431,13 +16422,6 @@ __metadata:
   languageName: node
   linkType: hard
 
-"dateformat@npm:1.0.4-1.2.3":
-  version: 1.0.4-1.2.3
-  resolution: "dateformat@npm:1.0.4-1.2.3"
-  checksum: 10c0/290dec607d80e0a7dbc22d0c2ad19db04ef8c50d1969689b4542bca91c7383e99eadfbca3bc38dab7e8d77e987cc017d051744fe7b29a8b0926b2fe7b4a667b2
-  languageName: node
-  linkType: hard
-
 "daterangepicker@npm:2.1.27":
   version: 2.1.27
   resolution: "daterangepicker@npm:2.1.27"