[fix][admin] Allow defaultNumPartitions for non-partitioned autoTopicCreation override

[ChimdumebiNebolisa]

Fixes #24998

Motivation

The namespace autoTopicCreation override validation rejects defaultNumPartitions whenever topicType=non-partitioned. This forces clients and infrastructure-as-code tools to conditionally omit the field, making shared configuration templates harder to maintain.

The relaxation is intentionally narrow. For non-partitioned overrides, defaultNumPartitions may be null, 0, or 1. Values greater than 1 remain invalid.

Accepted values are persisted as submitted but ignored during runtime topic creation. Auto-created topics therefore remain non-partitioned.

Modifications

• Updated AutoTopicCreationOverrideImpl.validateOverride to allow defaultNumPartitions for NON_PARTITIONED only when the value is null, 0, or 1.
• Added unit coverage confirming that 0 and 1 are accepted and 2 is rejected.
• Added broker-level coverage confirming that:
  • an accepted value of 1 is persisted but ignored when the topic is auto-created
  • a value of 5 is rejected by the admin REST API with HTTP 412

Verifying this change

./gradlew :pulsar-common:test \
  --tests "org.apache.pulsar.common.policies.data.AutoTopicCreationOverrideTest" \
  -PtestRetryCount=0

./gradlew :pulsar-broker:test \
  --tests "org.apache.pulsar.broker.admin.AdminApi2Test.testAutoTopicCreationOverrideNonPartitionedDefaultNumPartitionsIgnored" \
  --tests "org.apache.pulsar.broker.admin.AdminApi2Test.testAutoTopicCreationOverrideNonPartitionedDefaultNumPartitionsRejected" \
  -PtestRetryCount=0

./gradlew quickCheck

Does this pull request potentially affect one of the following parts:

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

• doc-not-needed

[ChimdumebiNebolisa]

Updated validateOverride to keep topic type validation and allow defaultNumPartitions for NON_PARTITIONED only when null, 0, or 1. Updated unit tests to cover 0, 1, and reject 2.

[lhotari]

Updated validateOverride to keep topic type validation and allow defaultNumPartitions for NON_PARTITIONED only when null, 0, or 1. Updated unit tests to cover 0, 1, and reject 2.

Please add this information to the PR description.

[lhotari]

LGTM, thanks for the contribution @ChimdumebiNebolisa

[lhotari]

shouldn't this fail?

[ChimdumebiNebolisa]

Updated this to address the review comment. The acceptance test now uses 1, and I added a separate test confirming that 5 is rejected with HTTP 412. The targeted tests and quickCheck pass locally. CI is currently awaiting maintainer approval.