Upgrade Spring Cloud Stream for Boot 2.7

[Ouweshs28]

What's changed?

• Upgrades spring-cloud-stream-dependencies to the Spring Boot 2.7-compatible 3.2.x release line.
• Adds positive and no-downgrade regression coverage for the Boot 1.5-to-2.7 migration.

What's your motivation?

• Fixes Support upgrades for Spring Cloud Stream #672. Spring Cloud Stream’s BOM was left at its legacy version after upgrading Spring Boot, causing runtime incompatibilities.

Anything in particular you'd like reviewers to focus on?

Please confirm that 3.2.x is the intended Spring Cloud Stream target for the Boot 2.7 migration.

Have you considered any alternatives or workarounds?

A standalone recipe was unnecessary because this is a narrowly scoped dependency-management upgrade specific to the existing Boot 2.7 composite recipe.

Any additional context

recipes.csv does not require an update because the existing recipe’s metadata did not change.

Checklist

• I've added unit tests to cover both positive and negative cases
• I've read and applied the recipe conventions and best practices
• I've run ./gradlew build locally, and committed any resulting changes to recipes.csv
• I've formatted the lines I changed, without reformatting code I didn't touch

[timtebeek]

Thanks @Ouweshs28 ; good to see that issue closed.