Remove/refactor scripts

[bdice]

There are some other scripts that seem unnecessary:

• update_gcc.sh can probably go away since the GCC version is 11.4 now
• rapids-colab.sh appears to target RAPIDS 21.06 and has notices about BlazingSQL. This can probably go away?
• env-check.py and pip-install.py seem to have a lot of duplicated logic. Let's simplify this.