[native/monodroid] Fix error demangling satellite assembly names (#9166)

When assemblies are packaged in the `.apk` archive, their names are
"mangled" so that we don't create clashes with "real" shared
libraries, which are placed into the same "directory."  Additionally,
since the `lib/` directory in the `.apk` archive supports only a
single level of directories, we must encode satellite assembly
culture in the file name, instead of putting it in a subdirectory.

Unfortunately, when the code was committed, an off-by-one error crept
in, when converting satellite assembly names to their `culture/name`
form.  As the result, the first character of the culture was omitted
which would cause the satellite assemblies not to be loaded properly.

Fix the issue by using the correct mangled name prefix length.

Author: grendello

src/native/monodroid/embedded-assemblies.hh

@@ -324,8 +324,7 @@ namespace xamarin::android::internal {
 		static constexpr size_t get_mangled_prefix_length ()
 		{
 			if constexpr (IsSatelliteAssembly) {
-				// +1 for the extra `-` char in the culture portion of satellite assembly's name;
-				return SharedConstants::MANGLED_ASSEMBLY_SATELLITE_ASSEMBLY_MARKER.length () + 1;
+				return SharedConstants::MANGLED_ASSEMBLY_SATELLITE_ASSEMBLY_MARKER.length ();
 			} else {
 				return SharedConstants::MANGLED_ASSEMBLY_REGULAR_ASSEMBLY_MARKER.length ();
 			}