fix: release pre-acquired stream IDs

[arnabnandy7]

Description

What changed

• Release pre-acquired stream IDs when DriverChannel.write() rejects a request before submitting it to the Netty pipeline.
• Release reservations when synchronous request construction fails before write() is called.
• Apply the same handling to:
  • CQL requests
  • prepare requests and secondary prepares
  • graph requests
  • continuous paging requests
• Release the reservation when a continuous paging callback completes after channel acquisition but before submission.
• Add regression coverage and update the changelog.

Root cause

Channel selection calls preAcquireId() before returning a channel. Request handlers then perform additional work before the resulting RequestMessage reaches InFlightHandler.

If that work throws, or DriverChannel.write() rejects the request before pipeline submission, InFlightHandler never sees the request and therefore cannot release the reservation. Repeated failures can cause available stream-ID accounting to drift and eventually make healthy channels appear saturated.

Impact

Every successful stream-ID pre-acquisition now ends in one of two outcomes:

• the request is submitted to InFlightHandler; or
• the reservation is explicitly released.

Fixes #947.

Validation

mvn -pl core -Dtest=DriverChannelTest,CqlRequestHandlerTest,CqlPrepareHandlerTest test

• 18 tests passed
• Formatter and Error Prone checks passed under JDK 17
• git diff --check passed

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Review details

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📥 Commits

Reviewing files that changed from the base of the PR and between 3cafb2a and 5900e56.

📒 Files selected for processing (8)

• changelog/README.md
• core/src/main/java/com/datastax/dse/driver/internal/core/cql/continuous/ContinuousRequestHandlerBase.java
• core/src/main/java/com/datastax/dse/driver/internal/core/graph/GraphRequestHandler.java
• core/src/main/java/com/datastax/oss/driver/internal/core/channel/DriverChannel.java
• core/src/main/java/com/datastax/oss/driver/internal/core/channel/InFlightHandler.java
• core/src/main/java/com/datastax/oss/driver/internal/core/cql/CqlPrepareHandler.java
• core/src/main/java/com/datastax/oss/driver/internal/core/cql/CqlRequestHandler.java
• core/src/test/java/com/datastax/oss/driver/internal/core/channel/DriverChannelTest.java

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[arnabnandy7]

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[dkropachev]

Closing in favor of #965. It covers the same #947 stream-id leak on scylla-4.x, includes the additional pre-acquired-id cleanup paths, and has focused test coverage plus the current CI compatibility fixes.