Exclude Rust FFI tests from Bazel glob pattern

The rust_disassembler_diagnostics_test and disassemble_rust_fallback_test
require Rust FFI headers (rust/cxxbridge/spirv-tools-ffi.h) which are
not available in the default Bazel test build configuration. Exclude
them from the glob like rust_validator_override_test.cpp.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: LegNeato

BUILD.bazel

@@ -520,6 +520,8 @@ cc_library(
         "test/pch_test.cpp",
         # Requires Rust FFI build (spirv_tools_enable_rust=true)
         "test/rust_validator_override_test.cpp",
+        "test/rust_disassembler_diagnostics_test.cpp",
+        "test/disassemble_rust_fallback_test.cpp",
     ],
 )]