Replace bundled gcloud_crcmod with system crcmod.
The Google Cloud SDK uses its bundled gcloud_crcmod module as a fallback
for CRC32C checksum calculations. Replace its imports with the system
crcmod package to avoid depending on the bundled implementation.
Preserve the existing google-crc32c fast-path selection and fallback
behavior.
--- ../lib/googlecloudsdk/command_lib/kms/crc32c.py	2026-10-19 11:21:01.034395166 +0300
+++ ../lib/googlecloudsdk/command_lib/kms/crc32c.py	2026-10-19 11:21:16.790663180 +0300
@@ -15,7 +15,7 @@
 """Helpers for calculating CRC32C checksums."""
 
 
-import gcloud_crcmod as crcmod
+import crcmod
 import six
 
 
--- ../lib/googlecloudsdk/command_lib/util/crc32c.py	2026-10-19 11:22:22.916056410 +0300
+++ ../lib/googlecloudsdk/command_lib/util/crc32c.py	2026-10-19 11:22:36.420141576 +0300
@@ -38,7 +38,7 @@
 except ImportError:
   # TODO(b/194124148) Fall back on pure Python google-crc32c.
   # Cleans up a lot of this file.
-  import gcloud_crcmod as crcmod
+  import crcmod
   IS_FAST_GOOGLE_CRC32C_AVAILABLE = False
 # pylint: enable=g-import-not-at-top