in_windows_eventlog2: remove trailing ':' and spaces at once

Signed-off-by: Shizuo Fujita <fujita@clear-code.com>

Author: Watson1978

lib/fluent/plugin/in_windows_eventlog2.rb

@@ -417,8 +417,7 @@ def parse_desc(record)
                          r.split(NONE_FIELD_DELIMITER)
                        end
           key = "" if key.nil?
-          key.strip! # parsed key sometimes contain unexpected " ". So remove it.
-          key.chop!  # remove ':' from key
+          key.sub!(/:\s*$/, '')  # remove ':' from key
           if value.nil?
             parent_key = to_key(key)
           else