Packaging: Use base64 key (#61802)

The tools in this repo need base64 but not in most other tools. I had to revert the change I made to the key
I created another key for base64 that we can use here
Follow-up to https://github.com/grafana/grafana/pull/61784

scripts/drone/vault.star

@@ -52,12 +52,12 @@ def secrets():
         vault_secret(
             'packages_gpg_public_key',
             'infra/data/ci/packages-publish/gpg',
-            'public-key',
+            'public-key-b64',
         ),
         vault_secret(
             'packages_gpg_private_key',
             'infra/data/ci/packages-publish/gpg',
-            'private-key',
+            'private-key-b64',
         ),
         vault_secret(
             'packages_gpg_passphrase',