user/ruby3.0-grpc: move from backports + use ruby 3.0

user/grpc/ruby-fix-protoc-path.patch

@@ -0,0 +1,25 @@
+Patch-Source: https://sources.debian.org/src/grpc/1.44.0-3/debian/patches/fix-protoc-path.patch (modified)
+
+--- a/src/ruby/end2end/package_with_underscore_test.rb
++++ b/src/ruby/end2end/package_with_underscore_test.rb
+@@ -20,8 +20,8 @@ def main
+   pb_dir = File.join(root_dir, 'src', 'ruby', 'end2end', 'protos')
+ 
+-  bins_dir = File.join(root_dir, 'cmake', 'build')
++  bins_dir = '/usr/bin'
+   plugin = File.join(bins_dir, 'grpc_ruby_plugin')
+-  protoc = File.join(bins_dir, 'third_party', 'protobuf', 'protoc')
++  protoc = File.join(bins_dir, 'protoc')
+ 
+   got = nil
+ 
+--- a/src/ruby/tools/bin/grpc_tools_ruby_protoc
++++ b/src/ruby/tools/bin/grpc_tools_ruby_protoc
+@@ -25,6 +25,5 @@ plugin_name = 'grpc_ruby_plugin' + ext
+ 
+-protoc_dir = File.join(File.dirname(__FILE__),
+-                       PLATFORM.architecture + '-' + PLATFORM.os_name)
++protoc_dir = '/usr/bin'
+ 
+ protoc_path = File.join(protoc_dir, protoc_name)
+