[ARM] Specify Triple in DebugInfo Tests

[ARM] Specify Triple in DebugInfo Tests

When the host's target triple ends in `-windows-msvc`, `%llc_dwarf`
contains an explicit `-windows-gnu` triple which ensures that dwarf will
be used. This is useful in target-independent tests, where no triple is
specified, and no target-specific features are used. However, this is
not compatible with target-dependent tests (such as those in
llvm/test/DebugInfo/ARM), as the command-line triple will override the
triple in the LLVM IR program, causing test issues on windows.

This change switches these tests to use an explicit triple, so the tests
test what was expected, and there is no flakiness on windows.

Fixes #58053

Differential Revision: https://reviews.llvm.org/D136066