Remove mentions of TC-0 that are not useful anymore

Pages that may be needed to be updated:

• https://assignments.lrde.epita.fr/instructions/groups.html
• https://assignments.lrde.epita.fr/instructions/submission.html
• https://assignments.lrde.epita.fr/compiler_stages/tc_2/code_to_write.html

This page must mention the move away from TC-0 starting from Tiger 2022:

• https://assignments.lrde.epita.fr/compiler_stages/pthl/pthl.html