Consolidate test_multidynamic_link and test_multiply_defined_libsymbols. NFC

[sbc100]

Since these tests were largely redundant, consolidate them into a single parameterized test. Specifically, test_multiply_defined_libsymbols was more comprehensive but test_multidynamic_link tested versioned suffixes and full path linking. test_multiply_defined_libsymbols now covers those cases.

[sbc100]

I suspected these two tests were redundant, so I had gemini analyze them and got these results.

I've confirmed that test_multidynamic_link and test_multiply_defined_libsymbols were largely redundant. Both were testing that Emscripten's "fake dylib" model (where .so files are treated
as object files) correctly handles multiple inclusions of the same library without causing multiple definition errors.

Comparison

• test_multiply_defined_libsymbols: A more comprehensive "diamond dependency" test (main -> liba2 -> libA, main -> libb2 -> libA, and main -> libA directly). It also explicitly verifies
  that emcc issues a warning when ignoring a dynamic library during intermediate object file generation.
• test_multidynamic_link: A simpler "chain dependency" test (main -> libother -> libfile). Its only unique contributions were testing versioned suffixes (e.g., .so.1.2.3) and linking by
  full path rather than -l.

Action Taken
I have consolidated the tests by:

1. Enhancing test_multiply_defined_libsymbols: Added parameterization to cover versioned suffixes and full path linking, ensuring no loss of coverage.
2. Removing test_multidynamic_link: Since its core logic and unique edge cases are now covered by the more robust test_multiply_defined_libsymbols, it has been removed.