Revert "Update opaque-keys library to use block_id for html_id for new k...

Reverts edx/edx-platform#4960
install_prereqs is now failing with:
```
pip install -q --exists-action w -r requirements/edx/github.txt
[...]
  Could not find a tag or branch '7152bcd9be8afb4accee9aa5d9d3c67d575f3e4e', assuming commit.
fatal: Could not parse object '7152bcd9be8afb4accee9aa5d9d3c67d575f3e4e'.
Command /usr/bin/git reset --hard -q 7152bcd9be8afb4accee9aa5d9d3c67d575f3e4e failed with error code 128 in /edx/app/edxapp/venvs/edxapp/src/opaque-keys
Storing debug log for failure in /edx/app/edxapp/.pip/pip.log
```