allow updates to secureJsonData.

SecureJsonData is stored as a json object in the DB. As the
secureJsonData is never returned to the user they are unable
to provide the full json object when performing updates instead
the user can only provide the specific keys they wish to update.
This commit ensures that only the provided keys are updated and
existing keys in the secureJsonData object are left untouched.

pkg/services/sqlstore/plugin_setting.go

@@ -61,7 +61,6 @@ func UpdatePluginSetting(cmd *m.UpdatePluginSettingCmd) error {
 			for key, data := range cmd.SecureJsonData {
 				pluginSetting.SecureJsonData[key] = util.Encrypt([]byte(data), setting.SecretKey)
 			}
-			pluginSetting.SecureJsonData = cmd.GetEncryptedJsonData()
 			pluginSetting.Updated = time.Now()
 			pluginSetting.Enabled = cmd.Enabled
 			pluginSetting.JsonData = cmd.JsonData