Remove manual kernel tagging in main client_ivc_prove flow

[ledwards2225]

The main flow used for IVC in the TS tests client_ivc_prove_output_all_msgpack now includes explicit tagging of every other circuit as a kernel. This used to be done automatically from within ClientIvc assuming auto_very_mode == true. In practice, the is_kernel tag will be set by the presence of calldata in the noir program. At the time of writing, this is already the case for the mock kernels in Alvaro's ivc integration suite. Once the databus has been integrated into the real kernel programs, we can do away with the explicit setting of is_kernel in that flow. (Note: we'll still need to use auto_very_mode until explicit verify_proof calls have been added to the kernels as well).