Don't fail scheduled outerloop builds on Helix work item failures

The libraries outerloop pipeline runs on a daily schedule with always:false,
meaning AzDO only re-queues a commit if there were changes since the last
successful scheduled run. Because flaky outerloop tests cause the 'Send to
Helix' task to fail on essentially every scheduled run, the build never
succeeds, so AzDO re-queues the same commit every day and submits ever more
Helix work for an unchanged sha.

Set shouldContinueOnError on the Send to Helix step for scheduled builds only
(Build.Reason == 'Schedule'), so Helix work item failures no longer fail the
build. Compile/build breaks still fail the build, and PR/CI/manual runs are
unaffected.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: mmitche

eng/pipelines/libraries/outerloop.yml

@@ -23,6 +23,10 @@ extends:
           parameters:
             jobTemplate: /eng/pipelines/common/global-build-job.yml
             helixQueuesTemplate: /eng/pipelines/libraries/helix-queues-setup.yml
+            # Don't fail scheduled builds on Helix work item failures. Otherwise a perpetually
+            # failing scheduled build (flaky outerloop tests) causes AzDO to re-queue the same
+            # commit every day, wasting Helix resources. See always:false on the schedule above.
+            shouldContinueOnError: ${{ eq(variables['Build.Reason'], 'Schedule') }}
             buildConfig: Release
             platforms:
             - ${{ if eq(variables['includeWindowsOuterloop'], true) }}:
@@ -58,6 +62,8 @@ extends:
             parameters:
               jobTemplate: /eng/pipelines/common/global-build-job.yml
               helixQueuesTemplate: /eng/pipelines/libraries/helix-queues-setup.yml
+              # Don't fail scheduled builds on Helix work item failures (see comment above).
+              shouldContinueOnError: ${{ eq(variables['Build.Reason'], 'Schedule') }}
               buildConfig: Debug
               platforms:
               - ${{ if eq(variables['includeWindowsOuterloop'], true) }}:
@@ -87,6 +93,8 @@ extends:
             parameters:
               jobTemplate: /eng/pipelines/common/global-build-job.yml
               helixQueuesTemplate: /eng/pipelines/libraries/helix-queues-setup.yml
+              # Don't fail scheduled builds on Helix work item failures (see comment above).
+              shouldContinueOnError: ${{ eq(variables['Build.Reason'], 'Schedule') }}
               buildConfig: Release
               platforms:
               - windows_x86