Correct naming for for switch/case pattern-matched captured variables

[roji]

Fixes #37465

[Copilot]

Pull request overview

This PR fixes issue #37465 by improving how EF Core names query parameters derived from captured variables in switch/case pattern matching expressions. The fix ensures that user-provided variable names are correctly extracted from compiler-generated field names containing angle brackets.

• Refactored parameter name sanitization logic to extract user variable names from compiler-generated angle bracket notation
• Added a new helper method SanitizeCompilerGeneratedName that intelligently handles compiler-generated names
• Added test coverage for switch/case pattern matching scenarios

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
src/EFCore/Query/Internal/ExpressionTreeFuncletizer.cs	Refactored parameter naming logic: moved angle bracket handling to a new SanitizeCompilerGeneratedName method that extracts user variable names, and added validation to ensure parameter names start with a letter or underscore
test/EFCore.Specification.Tests/Query/NorthwindMiscellaneousQueryTestBase.cs	Added test case Captured_variable_from_switch_case_pattern_matching to verify correct parameter naming for variables captured from switch/case pattern matching
test/EFCore.SqlServer.FunctionalTests/Query/NorthwindMiscellaneousQuerySqlServerTest.cs	Added SQL Server test baseline showing the expected SQL output with @customerId parameter
test/EFCore.Cosmos.FunctionalTests/Query/NorthwindMiscellaneousQueryCosmosTest.cs	Added Cosmos DB test baseline showing the expected query output

[Stephek]

@roji Thanks for the prompt fix. Do you know when the next release (that contains this fix) is scheduled?

[roji]

@Stephek see #37465 (comment). Since this affects a very narrow scenario and can be easily worked around (via an additional local variable), we likely won't be patching 10.0 with the fix (so 11.0 would be the first version with the fix). But if other users run into it, this may change.