[Tooling] Use separate GitHub token when localizing libs

[iangmaia]

See p1758259272770889-slack-CC7L49W13

Description

We've noticed during a release that using a fine-grained token for the woocommerce org now fails when trying to access private libraries in the localize_libs lane.

This PR then introduces the separate token AUTOMATTIC_GITHUB_TOKEN_READ_ONLY used only when calling android_download_file_by_version.

[AliSoftware]

I'm guessing you plan to soon push a commit to .mobile-secrets to add that AUTOMATTIC_GITHUB_TOKEN_READ_ONLY env var to it, right?

I haven't seen that commit in .mobile-secrets yet so just 🎗️ to maybe not merge this PR until it's added too.

[iangmaia]

I'm guessing you plan to soon push a commit to .mobile-secrets to add that AUTOMATTIC_GITHUB_TOKEN_READ_ONLY env var to it, right?

I haven't seen that commit in .mobile-secrets yet so just 🎗️ to maybe not merge this PR until it's added too.

I've requested a fine-grained token but it hasn't been approved yet.
For now and to be able to merge this in time for the release tomorrow, I'll use a classic token in .mobile-secrets and once the fine-grained one gets approved I'll replace it.