Chore: Increase number of backend test retries in grabpl to 5 in release pipelines (#34493)

* Increase number of backend test retries to 5

* Exclude release-branch pipelines

* Fixes according to reviewer's comments

* Refactor

* Remove unused arguments

* Remove magic number

scripts/lib.star

@@ -434,7 +434,12 @@ def build_plugins_step(edition, sign=False):
         ],
     }
 
-def test_backend_step(edition):
+def test_backend_step(edition, tries=None):
+    test_backend_cmd = './bin/grabpl test-backend --edition {}'.format(edition)
+    integration_tests_cmd = './bin/grabpl integration-tests --edition {}'.format(edition)
+    if tries:
+        test_backend_cmd += ' --tries {}'.format(tries)
+        integration_tests_cmd += ' --tries {}'.format(tries)
     return {
         'name': 'test-backend' + enterprise2_sfx(edition),
         'image': build_image,
@@ -445,9 +450,9 @@ def test_backend_step(edition):
             # First make sure that there are no tests with FocusConvey
             '[ $(grep FocusConvey -R pkg | wc -l) -eq "0" ] || exit 1',
             # Then execute non-integration tests in parallel, since it should be safe
-            './bin/grabpl test-backend --edition {}'.format(edition),
+            test_backend_cmd,
             # Then execute integration tests in serial
-            './bin/grabpl integration-tests --edition {}'.format(edition),
+            integration_tests_cmd,
         ],
     }