ci: add dgb/pool-pillars-port to CI + coin-matrix trigger filters

PRs/pushes targeting the DGB integration branch matched no workflow
trigger (only master, btc-embedded, dash-spv-embedded were listed), so
no CI was eligible. Additive: mirrors the per-coin practice for the other
integration branches. Revert = drop the two dgb/pool-pillars-port entries.

Author: frstrtr

.github/workflows/build.yml

@@ -2,10 +2,10 @@ name: CI
 
 on:
   push:
-    branches: [master, btc-embedded, dash-spv-embedded, windows-build, service-update]
+    branches: [master, btc-embedded, dash-spv-embedded, dgb/pool-pillars-port, windows-build, service-update]
     tags: ['v*']
   pull_request:
-    branches: [master, btc-embedded, dash-spv-embedded, dgb/slice4-skeleton]
+    branches: [master, btc-embedded, dash-spv-embedded, dgb/slice4-skeleton, dgb/pool-pillars-port]
 
 jobs:
   # ════════════════════════════════════════════════════════════════════════════

.github/workflows/coin-matrix.yml

@@ -13,9 +13,9 @@ name: Coin matrix
 
 on:
   push:
-    branches: [master, btc-embedded, dash-spv-embedded, windows-build, service-update]
+    branches: [master, btc-embedded, dash-spv-embedded, dgb/pool-pillars-port, windows-build, service-update]
   pull_request:
-    branches: [master, btc-embedded, dash-spv-embedded, dgb/slice4-skeleton]
+    branches: [master, btc-embedded, dash-spv-embedded, dgb/slice4-skeleton, dgb/pool-pillars-port]
 
 jobs:
   coin: