Migrate Spring Boot 4 MongoDB modular packages and test starters

[Kyran121]

Summary

Migrates the MongoDB-related auto-configuration packages and test starters to their Spring Boot 4.0 modular locations, and adds the dedicated MongoDB test starters conditionally based on which main starter and test-slice annotations are in use.

• Class renames (Spring Data Mongo auto-configuration):
  • MongoDataAutoConfiguration → DataMongoAutoConfiguration
  • MongoReactiveDataAutoConfiguration → DataMongoReactiveAutoConfiguration
  • MongoRepositoriesAutoConfiguration → DataMongoRepositoriesAutoConfiguration
  • MongoReactiveRepositoriesAutoConfiguration → DataMongoReactiveRepositoriesAutoConfiguration
• Package moves:
  • org.springframework.boot.autoconfigure.data.mongo → org.springframework.boot.data.mongodb.autoconfigure
  • org.springframework.boot.test.autoconfigure.data.mongo (@DataMongoTest, etc.) → org.springframework.boot.data.mongodb.test.autoconfigure
  • org.springframework.boot.actuate.autoconfigure.data.mongo (health contributor autoconfig) → org.springframework.boot.mongodb.autoconfigure.health
  • org.springframework.boot.actuate.autoconfigure.metrics.mongo → org.springframework.boot.mongodb.autoconfigure.metrics
  • org.springframework.boot.actuate.data.mongo (health indicators) → org.springframework.boot.mongodb.health
• New conditional test-starter recipes: AddSpringBootStarterDataMongoDbTest / AddSpringBootStarterDataMongoDbReactiveTest add spring-boot-starter-data-mongodb-test or -reactive-test based on which main starter (spring-boot-starter-data-mongodb vs -reactive) is present. This precondition is needed because @DataMongoTest is a single shared annotation for both imperative and reactive slices, so usage alone can't tell you which starter to add. Each recipe checks the test-slice annotation in both its pre- and post-migration package location, since these two recipes are independently invocable outside the full MigrateToModularStarters sequence — not just inline steps like the other technologies in this file.

This PR covers the Spring Boot-owned modular package and starter changes for MongoDB; Spring Data MongoDB API-level changes (e.g. UUID/BigDecimal representation defaults) are out of scope and tracked separately.

Verified against

Spring Boot 4.0 is GA. Its migration guide gives the root package prefix for each module via its module table (e.g. spring-boot-mongodb → org.springframework.boot.mongodb, spring-boot-data-mongodb → org.springframework.boot.data.mongodb) plus a generic "each module starts with org.springframework.boot.<module>" rule, but it doesn't map the specific internal sub-packages or renamed classes. Those mappings were checked directly against the released v4.0.7 source:

• Renamed autoconfig classes: module/spring-boot-data-mongodb/.../autoconfigure
• @DataMongoTest package: module/spring-boot-data-mongodb-test/.../autoconfigure
• Health contributor autoconfig: module/spring-boot-mongodb/.../autoconfigure/health
• Metrics autoconfig: module/spring-boot-mongodb/.../autoconfigure/metrics
• Health indicators: module/spring-boot-mongodb/.../health
• Starter/test-starter naming and property renames: migration guide, starter table

recipes.csv's count deltas (+9 on MigrateAutoconfigurePackages, +15 on MigrateToModularStarters) are the regenerated totals reflecting the new entries added here, not manual edits.

Test plan

• MigrateMongoDbModularStartersTest: imperative and reactive test-starter addition, negative cases for both (no starter added without matching test-slice usage), auto-configuration class renames, actuator package moves