Refactor source-build CI triggers and pools (#14835)

eng/source-build-tarball-build-official.yml

@@ -4,7 +4,14 @@ resources:
   pipelines:
   - pipeline: installer-build-resource
     source: dotnet-installer-official-ci
-    trigger: true
+    trigger:
+      branches:
+        include:
+        - main
+        - release/*
+        - internal/release/*
+      stages:
+      - build
 
 stages:
 - stage: build

src/SourceBuild/Arcade/eng/common/templates/job/source-build-create-tarball.yml

@@ -6,11 +6,20 @@ jobs:
   displayName: Source-Build Create Tarball
   pool:
     ${{ if eq(variables['System.TeamProject'], 'public') }}:
+      ${{ if in(variables['Build.Reason'], 'PullRequest') }}:
+        name: NetCore-Public-XL
+        demands: ImageOverride -equals Build.Ubuntu.1804.Amd64.Open
+      ${{ else }}:
         name: NetCore-Svc-Public
         demands: ImageOverride -equals Build.Ubuntu.1804.Amd64.Open
     ${{ if eq(variables['System.TeamProject'], 'internal') }}:
+      ${{ if in(variables['Build.Reason'], 'PullRequest') }}:
+        name: NetCore1ESPool-Internal-XL
+        demands: ImageOverride -equals Build.Ubuntu.1804.Amd64
+      ${{ else }}:
         name: NetCore1ESPool-Svc-Internal
         demands: ImageOverride -equals Build.Ubuntu.1804.Amd64
+
   variables:
   - name: _BuildConfig
     value: Release

src/SourceBuild/Arcade/eng/common/templates/job/source-build-run-tarball-build.yml

@@ -15,6 +15,9 @@ parameters:
   fedora36Container: mcr.microsoft.com/dotnet-buildtools/prereqs:fedora-36-20220818134137-a09384f
   ubuntu2004Container: mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-20.04-20220813234344-4c008dd
   poolInternalAmd64:
+    name: NetCore1ESPool-Svc-Internal
+    demands: ImageOverride -equals Build.Ubuntu.1804.Amd64
+  poolInternalAmd64PR:
     name: NetCore1ESPool-Internal-XL
     demands: ImageOverride -equals Build.Ubuntu.1804.Amd64
   poolInternalArm64:
@@ -68,6 +71,9 @@ jobs:
       ${{ if eq(variables['System.TeamProject'], 'public') }}:
         ${{ parameters.poolPublicAmd64 }}
       ${{ if eq(variables['System.TeamProject'], 'internal') }}:
+        ${{ if in(variables['Build.Reason'], 'PullRequest') }}:
+          ${{ parameters.poolInternalAmd64PR }}
+        ${{ else }}:
           ${{ parameters.poolInternalAmd64 }}
 
 - ${{ if eq(variables['System.TeamProject'], 'internal') }}: