test: enable TLA split-sync-modules tests that were previously skipped

Remove test.filter.js from split-sync-modules-{1,2,3} tests that were
skipped with "cycle caused by available modules". These tests exercise
the exact circular dependency scenario that extract_tla_shared_modules
now fixes.

Add warnings.js to expect the TLA circular dependency warning that is
emitted when shared modules are extracted.

Author: JSerFeng

tests/rspack-test/esmOutputCases/top-level-await/split-sync-modules-1/test.filter.js

@@ -0,0 +1 @@
+module.exports = [/Top-level await with shared modules caused a circular dependency/];

tests/rspack-test/esmOutputCases/top-level-await/split-sync-modules-1/warnings.js

@@ -0,0 +1 @@
+module.exports = [/Top-level await with shared modules caused a circular dependency/];

tests/rspack-test/esmOutputCases/top-level-await/split-sync-modules-2/test.filter.js

@@ -0,0 +1 @@
+module.exports = [/Top-level await with shared modules caused a circular dependency/];