Improve the format of record merge strategy ID

[https://github.com/apache/hudi/pull/11943#discussion_r1809697340]

Could we make the ID easier to read, e.g.,
"00000000-0000-0000-0000-000000000000": Avro payload based merging;
"00000000-0000-0000-0000-000000000001": overwrite with latest;
"00000000-0000-0000-0000-000000000002": event time ordering / default hoodie payload. Still reserve the existing ID as an alternative ID;
"00000000-0000-0000-0000-000000000003": validate duplicate key record merger;
etc.

Also is it necessary to use UUID format, maybe "0", "1", "2" are shorter IDs?

Another problem is, In the current scheme, it's still hard to avoid collision, since there is no rule on how to generate these IDs. A general String with namespace and number might be better.

## JIRA info

- Link: https://issues.apache.org/jira/browse/HUDI-8422
- Type: Sub-task
- Parent: https://issues.apache.org/jira/browse/HUDI-9108
- Fix version(s):
- 1.1.0