Enhance default build type selection

[sandro-elsweijer]

Describe your changes here:
Currently, the default build type in ccmake is not shown and the cmake build type is empty from the start. If it remains empty, release is chosen. This PR changes that, so release is displayed from the start and cannot be left empty.
Furthermore the docstring now lists our available build types, before it was the standard message which also listed MinSizeRel, which is not available in our list.

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As a reviewer please read through all the code lines and make sure that the code is fully understood, bug free, well-documented and well-structured.

General

• The reviewer executed the new code features at least once and checked the results manually

• The code follows the t8code coding guidelines

• New source/header files are properly added to the Makefiles

• The code is well documented

• All function declarations, structs/classes and their members have a proper doxygen documentation

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Tests

• The code is covered in an existing or new test case using Google Test

Github action

• The code compiles without warning in debugging and release mode, with and without MPI (this should be executed automatically in a github action)

• All tests pass (in various configurations, this should be executed automatically in a github action)

  If the Pull request introduces code that is not covered by the github action (for example coupling with a new library):

  • Should this use case be added to the github action?
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Scripts and Wiki

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Licence

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