[scripts] Fix terraform lint

Summary:
When reviewing D9877 I realized that terraform format lint doesn't work in pre-commit hook. Fixed this.
Also changed it to auto-format instead of failing.

Test Plan:
Made some formatting errors in terraform files, git staged them, and ran yarn lint-staged. It fixed them.

Output of terraform_pre_commit.sh (the modules/shared/dynamodb.tf was the file that was reformatted):

ᐅ ./scripts/terraform_pre_commit.sh
Formatting terraform...
modules/shared/dynamodb.tf
Validating 'dev' terraform configuration...
Success! The configuration is valid.

Validating 'remote' terraform configuration...
Success! The configuration is valid.

Reviewers: varun, wyilio

Reviewed By: varun

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D9958