[RF] Move vectorised PDF tests from roottest to roofit

[guitargeek]

These useful tests are relatively short (runtime 28 seconds in total) and test lower-level RooFit functionality.

Moving them from roottest to roofit has the following benefits:

• Faster RooFit development experience: it's not necessary anymore to also add and compile all of roottest, if you want to make sure locally that the vectorized pdf tests always compile and pass.

• The vectorized pdf tests will be able to consider the RooFit-internal preprocessor macros at build time, like ROOFIT_CUDA and ROOFIT_LEGACY_EVAL_BACKEND. Like this we can ensure that the tests will pass no matter how RooFit was configured at compile time. This is for me personally the strongest reason and was the motivator for this commit.

• Avoid code repetition in root and roottest, because now the vectorized PDF tests will be able to re-use private code from RooFit.

• If you want to build standalone RooFit with all tests, you won't have to stitch together the two repositories.

Sister PR: https://github.com/root-project/roottest/pull/1199

[github-actions[bot]]

Test Results

    12 files      12 suites   2d 6h 24m 17s :stopwatch:  2 662 tests  2 662 :white_check_mark: 0 :zzz: 0 :x: 30 576 runs  30 576 :white_check_mark: 0 :zzz: 0 :x:

Results for commit 6dd83ba8.