feat(session): Improve mysql session sql

[guanxuc]

AgentScope-Java Version

1.0.11

Description

• Closes: [Feature]: MysqlSession should use datetime(3) instead of timestamp to create table #991
• Closes: [Feature]: MysqlSession clearAllSessions should use truncate instead of delete from #992
• Use DATETIME instead of TIMESTAMP for mysql field
• Use TRUNCATE instead of DELETE from table

Checklist

Please check the following items before code is ready to be reviewed.

• Code has been formatted with mvn spotless:apply
• All tests are passing (mvn test)
• Javadoc comments are complete and follow project conventions
• Related documentation has been updated (e.g. links, examples, etc.)
• Code is ready for review

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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