Use consistent naming for environment variables that affect the EESSI module

Author: ocaisa

.github/workflows/tests_eessi_module.yml

@@ -343,7 +343,7 @@ jobs:
 
           export MODULEPATH=init/modules
           # Set the relevant environment variable, load the EESSI module, and grep for what we expect in PS1
-          export EESSI_UPDATE_PS1=1
+          export EESSI_MODULE_UPDATE_PS1=1
           # Need to set PS1 manually as we are in a non-interactive shell
           export PS1="mytest $"
           echo $PS1

init/modules/EESSI/2023.06.lua

@@ -216,7 +216,7 @@ end
 
 -- change the PS1 if it exists to indicate you have EESSI loaded
 -- (doesn't help with a csh or fish prompt, but we just live with that)
-if os.getenv("EESSI_UPDATE_PS1") then
+if os.getenv("EESSI_MODULE_UPDATE_PS1") then
     prompt = os.getenv("PS1")
     if prompt then
         pushenv("PS1", "{EESSI/" .. eessi_version .. "} " .. prompt)