hostedOPD: support configurable numVBuckets for Capella bucket creation

Add numVBuckets to the bucket spec and the Capella create_bucket
payload in hostedOPD.create_buckets, controlled by the 'numVBuckets'
test param (default 128). This lets aGoodDoctor volume tests create
Capella buckets with a specific vBucket count instead of relying on
the server-side default.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Change-Id: Ie9a0f3d8628bb8092637e596ad6acb51bd8f362c
Reviewed-on: https://review.couchbase.org/c/TAF/+/246616
Reviewed-by: Thuan Nguyen <soccon@gmail.com>
Tested-by: Ritesh Agarwal <ritesh.agarwal@couchbase.com>

Author: ritalrw

pytests/aGoodDoctor/hostedOPD.py

@@ -69,6 +69,7 @@ def create_buckets(self, pod, tenant, cluster, sdk_init=True):
                  Bucket.bucketType: bucket_type[i],
                  Bucket.durabilityMinLevel: self.bucket_durability_level,
                  Bucket.flushEnabled: True,
+                 Bucket.numVBuckets: self.input.param("numVBuckets", 128),
                  Bucket.fragmentationPercentage: self.fragmentation})
             self.bucket_params = {
                 "name": bucket.name,
@@ -78,6 +79,7 @@ def create_buckets(self, pod, tenant, cluster, sdk_init=True):
                 "replicas": bucket.replicaNumber,
                 "storageBackend": bucket.storageBackend,
                 "durabilityLevel": bucket.durabilityMinLevel,
+                "numVBuckets": bucket.numVBuckets,
                 "timeToLive": {"unit": "seconds", "value": bucket.maxTTL}
             }
             CapellaUtils.create_bucket(pod, tenant, cluster, self.bucket_params)