fix: Call set_ccl_vars_on_aurora only if WORLD_SIZE > 1

[saforem2]

This pull request includes changes to the setParams() function in the ALCF/helpers.sh file. The changes primarily involve the removal of outdated comments and code, and the addition of a conditional block to set CCL environment variables for Aurora when the world size is greater than 1.

Code cleanup and updates:

• Removed outdated comments and code related to setting CCL environment variables and using flash attention on Aurora.

Conditional environment variable setting:

• Added a conditional block to set the best set of CCL environment variables from Gordon Bell runs on Aurora when the world size is greater than 1.