Remove husky `HUSKY_GIT_PARAMS` fallback after some time

I'm upgrading the husky version to 9 which stops using `HUSKY_GIT_PARAMS` to pass git params in #6201 . But that PR still keeps this env variable as a fallback because we still have out of sync branches in our machines and we want to be able to safely switch between them for a while. I expect that we at least need to wait a few weeks up to a month until we can remove that.

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-1380)

Review the Husky v9 migration in #6201 and search the repository for HUSKY_GIT_PARAMS and its fallback usage. Remove the fallback after the branch-sync waiting period described in this issue, and confirm that the remaining Husky setup no longer depends on that environment variable.

Written by the indexing model from the issue text.