[FLINK-38207] Update Flink Operator to use JOSDK 5.1.2

[csviri]

This release fixes an issue with resource indexing on startup:

operator-framework/java-operator-sdk#2881

What does not necessarily create issues in practice, but can lead to inconsistent behavior

What is the purpose of the change

Bump JOSDK version to 5.1.2

Brief change log

Bump JOSDK version to 5.1.2

Verifying this change

This change is a trivial rework / code cleanup without any test coverage.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): yes
• The public API, i.e., is any changes to the CustomResourceDescriptors: no
• Core observer or reconciler logic that is regularly executed: no

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented? not applicable