Update oraclejdk manifests to oraclejdk-25 and oraclejdk-21 #566

JDK 25 is the latest Long-Term Support (LTS) release of the Java SE Platform.
JDK 21 is the previous Long-Term Support (LTS) release of the Java SE Platform.

Scoop bucket contains oraclejdk (25) and oraclejdk-lts (21), which raises two problems:

• User may mistakenly assume JDK 25 is not an LTS release;
• Oraclejdk (25) manifest will automatically upgrade to JDK 26 when available.

Proposal: Rename them to oraclejdk-25 and oraclejdk-21.
@se35710 Would you accept this change? I can submit a PR if approved, thanks a lot.