Revisit insertion point being restored by an InsertionGuard in `buildSwitchBody()`

[bcardosolopes]

          These tests are failing because the insertion point is restored by an InsertionGuard in `buildSwitchBody()`. I suggest revising that part after #528 is merged to avoid conflict.

clangir/clang/lib/CIR/CodeGen/CIRGenStmt.cpp

Lines 972 to 978 in 3da10fa

	} else if (lastCaseBlock) {
	// This means it's a random stmt following up a case, just
	// emit it as part of previous known case.
	mlir::OpBuilder::InsertionGuard guardCase(builder);
	builder.setInsertionPointToEnd(lastCaseBlock);
	res = buildStmt(c, /*useCurrentScope=*/!isa<CompoundStmt>(c));
	} else {

Originally posted by @piggynl in #611 (comment)

[bcardosolopes]

@piggynl somehow I cannot assign this issue to you, but here's an issue to track this.