refactor(wpcarro): Remove briefcase references

TL;DR:
- prefer WPCARRO env-var to BRIEFCASE
- remove repository URLs from Emacs libraries
- prefer tvl-depot-path where possible
- reduce the scope of constants.el
- prune (some not all) stale CI configuration

Change-Id: I21e9130402502ec6fa2fc4b46753c890069be62d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/4545
Tested-by: BuildkiteCI
Reviewed-by: wpcarro <wpcarro@gmail.com>

users/wpcarro/tools/symlinkManager/README.md

@@ -1,6 +1,6 @@
 # Dotfile Symlink Manager
 
-Find and delete all symlinks to the dotfiles defined in `$BRIEFCASE`.
+Find and delete all symlinks to my dotfiles.
 
 Oftentimes I corrupt the state of my configuration files. The intention with
 this script is to help me clean things up when this happens. An example workflow
@@ -9,6 +9,4 @@ might look like:
 ```shell
 > symlink-mgr --audit
 > symlink-mgr --seriously
-> briefcase # changes directory to $BRIEFCASE
-> make install
 ```