Change default value of -p flag in joblauncher.bash

[a-holla]

Currently, the default value of the partition argument in joblauncher.bash is set to 'ai', which leads to the following error:

sbatch: error: AssocGrpBillingMinutes sbatch: error: Batch job submission failed: Job violates accounting/QOS policy (job submit limit, user's size and/or time limits)

Either -p should be specified as 'cocosys', or the default value should be changed.

[amoghj98]

Default arg value modified to "cocosys"