Fix roottest-python-JupyROOT-importROOT intermittent hanging.
Fix roottest-python-JupyROOT-importROOT intermittent hanging.

importROOT and other Jupyter-related tests have been suffering from
intermittent timeouts. A deadlock has been identified in the JS code
that configures the syntax highlighting of the %%cpp cells.

Such feature is commented out until a solution is found to prevent it
from hanging. This should also solve the hanging on SWAN when
importing ROOT from a Python notebook.

BerserkerTroll/root,bbockelm/root,karies/root,davidlt/root,root-mirror/root,bbockelm/root,bbockelm/root,olifre/root,davidlt/root,BerserkerTroll/root,simonpf/root,simonpf/root,karies/root,davidlt/root,agarciamontoro/root,bbockelm/root,olifre/root,simonpf/root,agarciamontoro/root,simonpf/root,davidlt/root,davidlt/root,agarciamontoro/root,root-mirror/root,agarciamontoro/root,agarciamontoro/root,bbockelm/root,olifre/root,mhuwiler/rootauto,bbockelm/root,agarciamontoro/root,olifre/root,davidlt/root,mhuwiler/rootauto,olifre/root,BerserkerTroll/root,simonpf/root,olifre/root,mhuwiler/rootauto,BerserkerTroll/root,agarciamontoro/root,zzxuanyuan/root,bbockelm/root,davidlt/root,karies/root,mhuwiler/rootauto,simonpf/root,BerserkerTroll/root,root-mirror/root,agarciamontoro/root,olifre/root,olifre/root,BerserkerTroll/root,zzxuanyuan/root,olifre/root,root-mirror/root,zzxuanyuan/root,agarciamontoro/root,BerserkerTroll/root,davidlt/root,BerserkerTroll/root,bbockelm/root,simonpf/root,simonpf/root,karies/root,davidlt/root,karies/root,zzxuanyuan/root,karies/root,root-mirror/root,BerserkerTroll/root,karies/root,root-mirror/root,agarciamontoro/root,zzxuanyuan/root,davidlt/root,karies/root,bbockelm/root,root-mirror/root,simonpf/root,bbockelm/root,agarciamontoro/root,mhuwiler/rootauto,BerserkerTroll/root,zzxuanyuan/root,olifre/root,zzxuanyuan/root,mhuwiler/rootauto,bbockelm/root,mhuwiler/rootauto,root-mirror/root,root-mirror/root,zzxuanyuan/root,BerserkerTroll/root,mhuwiler/rootauto,mhuwiler/rootauto,mhuwiler/rootauto,olifre/root,mhuwiler/rootauto,root-mirror/root,davidlt/root,karies/root,zzxuanyuan/root,zzxuanyuan/root,karies/root,zzxuanyuan/root,zzxuanyuan/root,simonpf/root,root-mirror/root,karies/root,simonpf/root