Recombine osx and normal ci. (#23144)

* Some of the Windows runs have started to exceed 24 hours now as well as the MacOS ones as we have added more ports.
* We are no longer trying to constantly "psychic debug" why ports are failing; CI passes somewhat regularly now, and the failures we get seem to be much more deterministic.
* We're still budget constrained on Azure resources (and have been a bit over budget)

To that end, we're going back off nightly CI runs to Monday Wednesday Friday (like osx already is), so we no longer need separate bits for them.

scripts/azure-pipelines/azure-pipelines-osx.yml

@@ -1,10 +0,0 @@
-# Copyright (c) Microsoft Corporation.
-# SPDX-License-Identifier: MIT
-#
-variables:
-  osx-pool: 'PrOsx-2022-02-04'
-
-jobs:
-- template: osx/azure-pipelines.yml
-  parameters:
-    poolName: $(osx-pool)

scripts/azure-pipelines/azure-pipelines.yml

@@ -49,10 +49,9 @@ jobs:
     jobName: arm_uwp
     poolName: $(windows-pool)
 
-- ${{ if eq(variables['Build.Reason'], 'PullRequest') }}:
-  - template: osx/azure-pipelines.yml
-    parameters:
-      poolName: $(osx-pool)
+- template: osx/azure-pipelines.yml
+  parameters:
+    poolName: $(osx-pool)
 
 - template: linux/azure-pipelines.yml
   parameters: