Add PR trigger back to YAML

I think these previously worked without the YAML PR trigger because of
GUI setup that I messed up by changing the service connection.

Author: andyleejordan

Diff for: .vsts-ci/azure-pipelines-ci.yml

@@ -13,6 +13,9 @@ trigger:
     include:
       - master
 
+pr:
+- master
+
 jobs:
 - job: PS51_Win2016
   displayName: PowerShell 5.1 - Windows Server 2016

Diff for: .vsts-ci/misc-analysis.yml

@@ -5,6 +5,9 @@ trigger:
     include:
     - master
 
+pr:
+- master
+
 resources:
   repositories:
   - repository: ComplianceRepo