[FLINK-37406] Fix config array serialization

[csviri]

What is the purpose of the change

Fixes serialization of array values:

a: 1
b: 
  c: [1,2]

now becomes:

a: 1
b.c: 1;2

This change added tests;

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

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

Documentation

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