Delete numba/dppl after moving to numba-dppy/numba_dppy with all history

[PokhodenkoSA]

Commands:

1. Split history for numba/dppl, numba/dppy and numba/oneapi (Linux faster than Windows):
   git subtree split --prefix=numba/dppl --annotate="(numba/dppl) " -b dppl -> IntelPython/numba-dpex@fa996e3
   git checkout f5ccb0187^ (f5ccb01 - rename commit, commit^ - commit before)
   git subtree split --prefix=numba/dppy --annotate="(numba/dppy) " -b dppy -> IntelPython/numba-dpex@ad7d95c
   git checkout 600a1fdea^ (600a1fd)
   git subtree split --prefix=numba/oneapi --annotate="(numba/oneapi) " -b oneapi -> IntelPython/numba-dpex@c5b1917
2. Add remote https://github.com/IntelPython/numba-dppy.git and checkout main branch:
   git add remote numba-dppy https://github.com/IntelPython/numba-dppy.git
git checkout main numba-dppy/main
3. Add history folders:
   git subtree add --prefix=oneapi oneapi
git subtree add --prefix=dppy dppy
git subtree add --prefix=dppl dppl
4. Mount numba/dppl to numba_dppy and remove history folders:
   git subtree add --prefix=numba_dppy dppl
git rm oneapi dppy dppl
5. Push PR - Move numba/dppl to numba_dppy with all history numba-dpex#2

This PR removes numba/dppl