ci: avoid passing GPG passphrase on command line in Java publish workflow (#3313)

Fixes #3299

## Problem

Two security issues exist in `.github/workflows/java-publish.yml`:

1. **`gpg-passphrase` input is misused**: `actions/setup-java`'s
`gpg-passphrase` input expects the **name** of an environment variable
(default: `GPG_PASSPHRASE`), not the secret value itself. The previous
value `${{ secrets.GPG_PASSPHRASE }}` was setting the env var name to
the actual secret, which is incorrect.

2. **Passphrase visible on the command line**: `-Dgpg.passphrase=${{
secrets.GPG_PASSPHRASE }}` passes the GPG passphrase as a Maven system
property argument, making it visible in process listings and potentially
echoed in debug logs — a supply-chain security risk for release
workflows.

## Solution

- Fix `gpg-passphrase: MAVEN_GPG_PASSPHRASE` — use the correct env var
name so `actions/setup-java` generates a proper Maven `settings.xml`
entry that reads from `MAVEN_GPG_PASSPHRASE`.
- Remove `-Dgpg.passphrase=...` from the Maven CLI invocation.
- Add `MAVEN_GPG_PASSPHRASE: ${{ secrets.GPG_PASSPHRASE }}` to the
`env:` block of the Publish step, so the passphrase is available as an
environment variable rather than a CLI argument.

## Testing

The Java publish workflow only runs on tag pushes, so this cannot be
exercised in a PR build. The logic change is straightforward:
`actions/setup-java` is documented to write a `settings.xml` that reads
`<gpg.passphrase>` from the named env var, and `maven-gpg-plugin` picks
it up from there without any CLI argument.

Co-authored-by: octo-patch <octo-patch@github.com>

.github/workflows/java-publish.yml

@@ -43,7 +43,7 @@ jobs:
           server-username: SONATYPE_USER
           server-password: SONATYPE_TOKEN
           gpg-private-key: ${{ secrets.GPG_PRIVATE_KEY }}
-          gpg-passphrase: ${{ secrets.GPG_PASSPHRASE }}
+          gpg-passphrase: MAVEN_GPG_PASSPHRASE
       - name: Set git config
         run: |
           git config --global user.email "dev+gha@lancedb.com"
@@ -58,10 +58,11 @@ jobs:
           echo "use-agent" >> ~/.gnupg/gpg.conf
           echo "pinentry-mode loopback" >> ~/.gnupg/gpg.conf
           export GPG_TTY=$(tty)
-          ./mvnw --batch-mode -DskipTests -DpushChanges=false -Dgpg.passphrase=${{ secrets.GPG_PASSPHRASE }} deploy -pl lancedb-core -am -P deploy-to-ossrh
+          ./mvnw --batch-mode -DskipTests -DpushChanges=false deploy -pl lancedb-core -am -P deploy-to-ossrh
         env:
           SONATYPE_USER: ${{ secrets.SONATYPE_USER }}
           SONATYPE_TOKEN: ${{ secrets.SONATYPE_TOKEN }}
+          MAVEN_GPG_PASSPHRASE: ${{ secrets.GPG_PASSPHRASE }}
 
   report-failure:
     name: Report Workflow Failure