Make Micrometer optional

[fmbenhassine]

As of v5.2, Micrometer is a compile time dependency. Based on users feedback (similar to #3629), this seems to be a hard constraint. v6 is a good opportunity to review this and make Micrometer optional. Moreover, with #4972 , it should be possible for users to choose which observability option they would like to use without including the other.

[snicoll]

Please review this as the snapshot breaks the spring boot build, see this build scan.

DefaultBatchConfiguration still refers to JobOperatorFactoryBean which itself has a dependency to MeterRegistry.

[fmbenhassine]

DefaultBatchConfiguration still refers to JobOperatorFactoryBean which itself has a dependency to MeterRegistry.

Indeed. Moreover, spring-context seems to have a compile-time dependency to micrometer-observation, and spring-batch-core depends on spring-context. So I don't think making Micrometer optional is possible with the current state of things.

This was reverted.