Split rolling and PR builds. Drop ARM64, X86 from PR. (#5256)

## Summary of the Pull Request
Edits the definition file to distinguish further between the rolling build (the one that happens in master as it's updated) and the PR builds (that happen on every push to a pull request to master.) We will build less in PR since it rolls so often by removing the lines that reveal very few to no bugs at PR time. We'll leave them on in rolling so stuff can still be caught.

## PR Checklist
* [x] Closes a desire to not waste builds.
* [x] I work here.
* [ ] We'll see if the build still works.
* [x] No specific docs.
* [x] I talked about this with @DHowett-MSFT already.

## Validation Steps Performed
* [x] This PR itself should validate that the definition still works in PRs. I think we have to wait for it to go to master to see if the trigger still works there.

build/pipelines/ci.yml

@@ -27,21 +27,43 @@ variables:
 #     0.0.1904.0900
 name: 0.0.$(Date:yyMM).$(Date:dd)$(Rev:rr)
 
-jobs:
-  - template: ./templates/build-console-audit-job.yml
-    parameters:
-      platform: x64
+stages:
+  - stage: Audit_x64
+    displayName: Audit Mode
+    dependsOn: []
+    condition: succeeded()
+    jobs:
+      - template: ./templates/build-console-audit-job.yml
+        parameters:
+          platform: x64
+  - stage: Build_x64
+    displayName: Build x64
+    dependsOn: []
+    condition: succeeded()
+    jobs:
+      - template: ./templates/build-console-ci.yml
+        parameters:
+          platform: x64
+  - stage: Build_x86
+    displayName: Build x86
+    dependsOn: []
+    condition: not(eq(variables['Build.Reason'], 'PullRequest'))
+    jobs:
+      - template: ./templates/build-console-ci.yml
+        parameters:
+          platform: x86
+  - stage: Build_ARM64
+    displayName: Build ARM64
+    dependsOn: []
+    condition: not(eq(variables['Build.Reason'], 'PullRequest'))
+    jobs:
+      - template: ./templates/build-console-ci.yml
+        parameters:
+          platform: ARM64
+  - stage: Scripts
+    displayName: Code Health Scripts
+    dependsOn: []
+    condition: succeeded()
+    jobs:
+      - template: ./templates/check-formatting.yml
 
-  - template: ./templates/build-console-ci.yml
-    parameters:
-      platform: x64
-
-  - template: ./templates/build-console-ci.yml
-    parameters:
-      platform: x86
-
-  - template: ./templates/build-console-ci.yml
-    parameters:
-      platform: ARM64
-
-  - template: ./templates/check-formatting.yml