Add range flag settings to class files (#5556)

Where `--no-dump-sem-ir` is used, change to `--dump-sem-ir-ranges=only`.
Otherwise, add `--dump-sem-ir-ranges=if-present` with a TODO to change
to `only`.

Note, SemIR is affected just because the extra comments change line
numbers in files where splits aren't in use.

toolchain/check/testdata/class/fail_method_modifiers.carbon

@@ -2,6 +2,9 @@
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
+// TODO: Add ranges and switch to "--dump-sem-ir-ranges=only".
+// EXTRA-ARGS: --dump-sem-ir-ranges=if-present
+//
 // AUTOUPDATE
 // TIP: To test this file alone, run:
 // TIP:   bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/check/testdata/class/fail_method_modifiers.carbon