Merge bitcoin/bitcoin#34859: ci: Retry on intermittent Windows generate download failures

fa71c6e84c ci: Avoid intermittent Windows generate download failures (MarcoFalke)

Pull request description:

  The CI Windows step to generate the build system is problematic, because with a clean cache, it will download artifacts over the network. This may intermittently fail due to intermittent network issues.

  Fix this issue, like all other network issues in CI, by retrying once.

ACKs for top commit:
  hodlinator:
    ACK fa71c6e84c
  hebasto:
    ACK fa71c6e84c, I have reviewed the code and it looks OK.

Tree-SHA512: 9915e84b6015116cce86a25b4f77e545baef1f26fabe767c8bb07a009b075f76c27f9172dd23f78aa8017fd611cea850b1e985a357bd0b24543e63e1fd85cb6d

.github/ci-windows.py

@@ -8,6 +8,7 @@ import os
 import shlex
 import subprocess
 import sys
+import time
 from pathlib import Path
 
 sys.path.append(str(Path(__file__).resolve().parent.parent / "test"))
@@ -73,7 +74,12 @@ def generate(ci_type):
         "--preset",
         "vs2026",
     ] + GENERATE_OPTIONS[ci_type]
-    run(command)
+    if run(command, check=False).returncode != 0:
+        print("=== ⚠️ ===")
+        print("Generate failure! Network issue? Retry once ...")
+        time.sleep(12)
+        print("=== ⚠️ ===")
+        run(command)
 
 
 def build(_ci_type):