Merge pull request #40586 from thaJeztah/19.03_revert_jenkinsfile_pin_older_windows

[19.03] Revert "Jenkinsfile: temporarily pin windows image to 10.0.17763.973"
diff --git a/Jenkinsfile b/Jenkinsfile
index 70117fe..8a0ad0c 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -829,7 +829,7 @@
                         TESTRUN_DRIVE          = 'd'
                         TESTRUN_SUBDIR         = "CI"
                         WINDOWS_BASE_IMAGE     = 'mcr.microsoft.com/windows/servercore'
-                        WINDOWS_BASE_IMAGE_TAG = '10.0.17763.973' // TODO switch back to using ltsc2019 once the image is fixed
+                        WINDOWS_BASE_IMAGE_TAG = 'ltsc2019'
                     }
                     agent {
                         node {