[CANCELLED][VOTE] Release Apache Paimon 1.2.0, release candidate #1

[yu zelin]

Hello Paimon devs,

Apache Paimon 1.2.0 rc1 was cancelled because of this PR
<https://github.com/apache/paimon/pull/5751>. I will cherry pick it to
release branch and start RC2 ASAP.

Best,
Zelin Yu