5059: WMS-T dimensions not loading

[FilipLeitner]

Description

• fix race conditions of layerDimensionDefinitionChanges. After mapEventHandlersSet emition layerDescriptors for default_layer should be available and setupTimeLayer should be executed correctly
• Simpify dimensions component value update by merging/debouncing subscribtions of layerDescriptor and layerDimensionDefinitionChanges . Replaced ngOnChange handler as well as I was not really followiing why its necessary (no inputs)

Related issues or pull requests

fixes #5059

Pull request type

Please check the type of change your PR introduces:

• [x] Bugfix
• [ ] Feature
• [ ] Dependency updates
• [ ] Code style update (formatting, renaming)
• [x] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] Documentation content changes
• [ ] Other (please describe)
• [ ] I am unsure (we'll look into it together)

Do you introduce a breaking change?

• [ ] Yes
• [ ] No
• [ ] I am unsure (no worries, we'll find out)

Checklist

• [x] I understand and agree that the changes in this PR will be licensed under the [MIT License]
• [ ] I have followed the guidelines for contributing
• [ ] The proposed change fits to the content of the code of conduct
• [ ] I have added or updated tests and documentation, and the test suite passes (run npm test locally)
• [ ] I'm lost; why do I have to check so many boxes? Please help!

[FilipLeitner]

Preferably need to be tested in other scenarios other the one in test-app