Add cargo profile env var to scripts/localnet.sh

[felipelincoln]

Description

Step 5 of bittensor-subnet-template/docs/running_on_staging.md says to build the subtensor with --profile production and then run scripts/localnet.sh which has a hardcoded profile release.
This PR allows running localnet with CARGO_PROFILE env variable, where the default goes back to release.

Usage example:

BUILD_BINARY=0 CARGO_PROFILE=production ./scripts/localnet.sh 

Related Issue(s)

• Closes ./scripts/localnet.sh looks for "release" directory  bittensor-subnet-template#118

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Other (please describe):

Checklist

• I have performed a self-review of my own code
• Not applicable - I have commented my code, particularly in hard-to-understand areas
• Not applicable - I have run cargo fmt and cargo clippy to ensure my code is formatted and linted correctly
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Not applicable - I have added tests that prove my fix is effective or that my feature works
• Not applicable - New and existing unit tests pass locally with my changes
• Not applicable - Any dependent changes have been merged and published in downstream modules

Additional Notes

PR updating documentation: opentensor/bittensor-subnet-template#137