Broadcast DistSQL create and drop executors match table names case-sensitively

[thswlsqls]

Bug Report

Which version of ShardingSphere did you use?

master @ 6621687

Which project did you use? ShardingSphere-JDBC or ShardingSphere-Proxy?

Both

Expected behavior

Broadcast table names are matched case-insensitively (core BroadcastRule.tables is a CaseInsensitiveSet). Creating a broadcast rule for T_ORDER when t_order exists should raise DuplicateRuleException, and dropping T_ORDER should remove t_order.

Actual behavior

The DistSQL create and drop executors compare table names case-sensitively:

• CREATE: the duplicate check misses T_ORDER vs t_order, no DuplicateRuleException is thrown, and both cases get stored.
• DROP: the existence check (case-insensitive) passes, but hasAnyOneToBeDropped (case-sensitive) reports nothing to drop, a silent no-op.

Reason analyze (If you can)

CreateBroadcastTableRuleExecutor.getDuplicatedRuleNames() copies rule tables into a case-sensitive HashSet before retainAll. DropBroadcastTableRuleExecutor.hasAnyOneToBeDropped() runs Collections.disjoint on the raw case-sensitive collection. Its own existence check and the sibling DropMaskRuleExecutor already wrap current tables in CaseInsensitiveSet (drop path partially fixed in #30180).

Steps to reproduce the behavior, such as: SQL to execute, sharding rule configuration, when exception occur etc.

1. CREATE BROADCAST TABLE RULE t_order;
2. CREATE BROADCAST TABLE RULE T_ORDER;
3. DROP BROADCAST TABLE RULE T_ORDER;

Example codes for reproduce this issue (such as a github link).

N/A