Subscription: Rename topic modes to initial and incremental

[Caideyipi]

Description

Rename canonical topic modes

• Add initial for full snapshot plus incremental data and make it the default mode.
• Add incremental for incremental-only subscriptions.
• Update ConfigNode, DataNode, examples, messages, and integration-test configurations to use the new names.

Preserve backward compatibility

• Continue accepting live as an alias of initial.
• Continue accepting consensus as an alias of incremental.
• Keep the old constants and mode predicates as deprecated APIs.
• Normalize aliases to canonical values so altering an existing legacy topic to the new name is not treated as a mode change.
• Keep mapping initial to the Pipe source's internal live mode.

Validation

• mvn test -pl iotdb-client/subscription -Dtest=TopicConfigTest
• mvn test -pl iotdb-client/subscription -P with-zh-locale -Dtest=TopicConfigTest
• SubscriptionInfoTopicValidationTest: 25 tests passed through targeted JUnit execution.
• mvn compile -pl example/subscription -Ddevelocity.off=true
• Spotless applied to the modified subscription, ConfigNode/DataNode, and integration-test sources.
• English/Chinese message constant parity verified.
• git diff --check

The standard ConfigNode Maven test command is currently blocked during compilation by the pre-existing PipeConfigNodeTaskAgent.getProgressIndexByType(...) error, before the targeted test executes.

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This PR has:

• been self-reviewed.
• added comments explaining compatibility behavior where it is not obvious.
• added or updated unit tests for the new and legacy mode values.
• updated existing integration-test configurations to use the canonical names.

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Key changed/added classes (or packages if there are too many classes) in this PR

• TopicConstant
• TopicConfig
• SubscriptionInfo
• ConfigNode/DataNode subscription runtime handling
• Subscription examples and integration tests