ci: rerun failed integration tests once to handle flaky failures (#9118)

The nightly `azure-dev - cli` pipeline has been red on nearly every run
because integration tests provision live Azure resources and fail
intermittently for environmental reasons that rotate night to night
(credential token expiry during long provisioning, transient Azure
service capacity such as App Service "No available instances to satisfy
this request", and teardown races). With no retry, a single such blip
fails the whole nightly.

Enable gotestsum's rerun of failed integration tests (once), so flaky
failures are retried while genuine regressions still fail:

- --rerun-fails=1: re-run each failed test one time.
- --rerun-fails-max-failures=5: if the initial run has more than 5
  failures, don't rerun anything (a mass failure is a real regression,
  not flake).
- --rerun-fails-report: record which tests were rerun so flaky tests
  stay visible for triage.
- --packages "./...": required by --rerun-fails (the package list can no
  longer be passed positionally after --).

Only the integration test invocation is changed; unit tests are fast and
deterministic and keep running without retry.

Fixes #8386

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

Author: vhvb1989

cli/azd/ci-test.ps1

@@ -4,7 +4,8 @@ param(
     [string] $IntegrationTestTimeout = '120m',
     [string] $IntegrationTestCoverageDir = 'cover-int',
     [string] $UnitTestTimingFile = 'test-timing-unit.json',
-    [string] $IntegrationTestTimingFile = 'test-timing-int.json'
+    [string] $IntegrationTestTimingFile = 'test-timing-int.json',
+    [string] $IntegrationTestRerunReport = 'test-rerun-int.txt'
 )
 
 $ErrorActionPreference = 'Stop'
@@ -62,7 +63,22 @@ $env:GOCOVERDIR = $intCoverDir.FullName
 $env:GOEXPERIMENT=""
 
 try {
-    & $gotestsum --jsonfile $IntegrationTestTimingFile -- ./... -v -timeout $IntegrationTestTimeout
+    # Integration tests provision live Azure resources and are prone to flaky, environmental
+    # failures (credential token expiry during long provisioning, transient Azure service
+    # capacity such as App Service "No available instances", teardown races). A single such
+    # blip currently reds the whole nightly run. Re-run failed tests once to distinguish flaky
+    # failures from real regressions. See https://github.com/Azure/azure-dev/issues/8386
+    #
+    # --rerun-fails requires the package list to be passed via --packages instead of positionally.
+    # --rerun-fails-max-failures caps reruns so a mass failure (a genuine regression) is not masked.
+    # --rerun-fails-report records which tests were rerun so flaky tests remain visible for triage.
+    & $gotestsum `
+        --jsonfile $IntegrationTestTimingFile `
+        --rerun-fails=1 `
+        --rerun-fails-max-failures=5 `
+        --rerun-fails-report $IntegrationTestRerunReport `
+        --packages "./..." `
+        -- -v -timeout $IntegrationTestTimeout
     if ($LASTEXITCODE) {
         exit $LASTEXITCODE
     }