[FIXUP] Favor uri_to_local_path; delete mnt_point

For MiqLocalMountSession, favor using uri_to_local_path when it does the
same thing as `File.join(mnt_point, relative_to_mount(remote_file))`,
which saves a decent amount of uncessary code by having to override
`mnt_point`.

This should behave the same on NFS and SMB as it did previously, but
then avoid the code changes for `mnt_point`, which isn't used terribly
consistently compared to the instance variable.

Ideally, we would want to use avoid the least amount of changes for
MiqGenericMountSession as well as the least amount of overrides in
MiqLocalMountSession, and I think this does that... I hope.

lib/gems/pending/util/mount/miq_generic_mount_session.rb

@@ -294,7 +294,7 @@ def download_single(remote_file, local_file)
 
     begin
       reconnect!
-      relpath = File.join(mnt_point, relative_to_mount(remote_file))
+      relpath = uri_to_local_path(remote_file)
       unless File.exist?(relpath)
         logger.warn("#{log_header} Remote file: [#{remote_file}] does not exist!")
         return

lib/gems/pending/util/mount/miq_local_mount_session.rb

@@ -18,31 +18,11 @@ def disconnect; end   # :nodoc:
   def mount_share; end  # :nodoc:
   # rubocop:enable Style/SingleLineMethods, Layout/EmptyLineBetweenDefs
 
-  def relative_to_mount(dest_uri) # :nodoc:
-    dest_uri
+  def relative_to_mount(remote_file) # :nodoc:
+    remote_file
   end
 
-  def uri_to_local_path(dest_uri) # :nodoc:
-    File.expand_path(dest_uri)
-  end
-
-  # :nodoc:
-  #
-  # This is an override to allow methods that make use of `@mnt_point` to
-  # behave as we would expect them to.
-  #
-  # Determine the mount point relative to the destination file, and just remove
-  # the portions of the expanded path that already exist in the
-  # `remote_file_path` (might be everything if `remote_file_path` is a absolute
-  # path)
-  def mnt_point
-    @mnt_point ||= begin
-                     path_str = if remote_file_path.kind_of?(IO)
-                                  remote_file_path.path
-                                else
-                                  remote_file_path.to_s
-                                end
-                     File.expand_path(path_str).sub(path_str, "")
-                   end
+  def uri_to_local_path(remote_file) # :nodoc:
+    File.expand_path(remote_file)
   end
 end