fix: remove escape from TOWER_ACCESS_TOKEN env var

[ejseqera]

Fixes the following error when running on GCP:

Command error:
  /mnt/disks/nf-tower-test-eu-1/scratch/2CqabFbg1cVUxD/14/2844a1e3d4392d478f740b92d2f367/.command.sh: line 4: TOWER_ACCESS_TOKEN: unbound variable

When we escape the TOWER_ACCESS_TOKEN variable with \, Google Batch interprets that as a literal string instead of performing variable substitution and craps out. Removal of this results in a successful run as we are able to authenticate, but Batch performs variable expansion during script execution before logging occurs so the token is shown in the logs.

Probably not the best practice but I am not sure of how to workaround this. Any ideas?

[ejseqera]

After some testing, it is fine to merge this in to allow nf-aggregate to be run on GCP without being concerned about the access token being exposed in the logs or elsewhere.

The expectation is that users will not have to explicitly specify an access token but instead use the ephemeral access token available on the head node when running through the Platform. This access token expires after about 1hr after so even if it is exposed in the logs, it is not valid thereafter nor is it tied to any specific user.