clang-format: Disable namespace indentation and omit {} in if/for/while

1. Disables namespace indentation in accordance with 16. of (*) and the
   majority of the codebase.
2. Disables {} for single-statement if/for/while in accordance with 17.
   of (*) and the majority of the codebase.

Note: clang-format is used manually and voluntarily, usually only on new
files. Nothing is automatically reformatted, this is only about how new
files look.

Motivated by https://github.com/ClickHouse/ClickHouse/pull/54115#discussion_r1322741846.

(*) https://clickhouse.com/docs/en/development/style#formatting

.clang-format

@@ -79,7 +79,7 @@ IndentWidth: 4
 IndentWrappedFunctionNames: false
 MacroBlockBegin: ''
 MacroBlockEnd: ''
-NamespaceIndentation: Inner
+NamespaceIndentation: None
 ObjCBlockIndentWidth: 4
 ObjCSpaceAfterProperty: true
 ObjCSpaceBeforeProtocolList: true
@@ -89,6 +89,7 @@ PenaltyBreakFirstLessLess: 120
 PenaltyBreakString: 1000
 PenaltyExcessCharacter: 1000000
 PenaltyReturnTypeOnItsOwnLine: 60
+RemoveBracesLLVM: true
 SpaceAfterCStyleCast: false
 SpaceBeforeAssignmentOperators: true
 SpaceBeforeParens: ControlStatements