Fix R2RDump to correctly parse array lower bounds (dotnet/coreclr#26743)

Fix R2RDump to correctly parse array lower bounds (dotnet/coreclr#26743)

There is a an incorrect size (likely a typo) used to create lower bounds
array when parsing signatures. This results in `Index was outside the
bounds of the array.` being printed inside of the array signature
string.

Commit migrated from https://github.com/dotnet/coreclr/commit/afd8b1f80a90a37d6b73987cbf9fdf03e8945250