Fix a possible logical error in ip_trie dictionary when key type is not String

[bharatnc]

The ip_trie dictionary read path always produces a plain ColumnString for the key regardless of the declared key type. When the key is declared as anything other than String (e.g. Nullable(String)), the mismatch between the block header type and actual column type causes a bad cast from ColumnString to ColumnNullable in SerializationNullable::enumerateStreams.

This seems to only affect direct table reads (eg. SELECT ... FROM dict) because:

• CREATE DICTIONARYdefers loading until first access
• dictGet()-style queries use a separate lookup path (getColumn) that never reaches keyViewGetter.

The fix validates the key type in keyViewGetter and rejects anything that is not String.

Possibly one of the related fixes for: #97454 (repro and check: #97454 (comment))

Changelog category (leave one):

• Bug Fix (user-visible misbehavior in an official stable release)

Changelog entry (a user-readable short description of the changes that goes into CHANGELOG.md):

Fix a possible logical error in ip_trie dictionary when key type is not String.

Documentation entry for user-facing changes

• Documentation is written (mandatory for new features)

[clickhouse-gh]

Workflow [PR], commit [2118632]

Summary: ❌

job_name	test_name	status	info	comment
Stateless tests (amd_tsan, parallel, 2/2)		failure
	02932_refreshable_materialized_views_2	FAIL	cidb, issue	ISSUE CREATED