refactor(tests): fix conflict of variable scope by renaming local variables during upgrade of groovy 3.x

[j-sandy]

While upgrading groovy 3.0.10 and spockframework 2.0-groovy-3.0, encountered the following errors in groovy test compilation of echo-core and echo-notifications modules:

startup failed:
/echo/echo-core/src/test/groovy/com/netflix/spinnaker/echo/notification/AbstractEventNotificationAgentSpec.groovy: 42: The current scope already contains a variable of the name event
 @ line 42, column 43.
   Mock.sendNotifications(*_) >> { notifica
                                 ^
1 error
> Task :echo-core:compileTestGroovy FAILED

startup failed:
/echo/echo-notifications/src/test/groovy/com/netflix/spinnaker/echo/notification/GithubNotificationAgentSpec.groovy: 50: The current scope already contains a variable of the name status
 @ line 50, column 31.
       github.updateCheck(*_) >> { token, repo, sha, status ->
                                 ^
1 error
> Task :echo-notifications:compileTestGroovy FAILED

startup failed:
/echo/echo-notifications/src/test/groovy/com/netflix/spinnaker/echo/notification/GithubNotificationAgentSpec.groovy: 99: The current scope already contains a variable of the name status
 @ line 99, column 31.
       github.updateCheck(*_) >> { token, repo, sha, status ->
                                 ^
1 error
> Task :echo-notifications:compileTestGroovy FAILED

startup failed:
/echo/echo-notifications/src/test/groovy/com/netflix/spinnaker/echo/notification/GoogleChatNotificationAgentSpec.groovy: 63: The current scope already contains a variable of the name webhookURL
 @ line 63, column 35.
       googleChat.sendMessage(*_) >> { webhookURL, message ->
                                     ^
/echo/echo-notifications/src/test/groovy/com/netflix/spinnaker/echo/notification/GoogleChatNotificationAgentSpec.groovy: 63: The current scope already contains a variable of the name message
 @ line 63, column 35.
       googleChat.sendMessage(*_) >> { webhookURL, message ->
                                     ^
2 errors
> Task :echo-notifications:compileTestGroovy FAILED

> Task :echo-notifications:compileTestGroovy FAILED
startup failed:
/echo/echo-notifications/src/test/groovy/com/netflix/spinnaker/echo/notification/GoogleChatNotificationAgentSpec.groovy: 92: The current scope already contains a variable of the name webhookURL
 @ line 92, column 35.
       googleChat.sendMessage(*_) >> { webhookURL, message ->
                                     ^
1 error

startup failed:
/echo/echo-notifications/src/test/groovy/com/netflix/spinnaker/echo/notification/SlackNotificationAgentSpec.groovy: 36: The current scope already contains a variable of the name channel
 @ line 36, column 30.
       slack.sendMessage(*_) >> { message, channel, asUser ->
                                ^
1 error
> Task :echo-notifications:compileTestGroovy FAILED

> Task :echo-notifications:compileTestGroovy FAILED
startup failed:
/echo/echo-notifications/src/test/groovy/com/netflix/spinnaker/echo/notification/SlackNotificationAgentSpec.groovy: 62: The current scope already contains a variable of the name message
 @ line 62, column 30.
       slack.sendMessage(*_) >> { message, channel, asUser ->
                                ^
/echo/echo-notifications/src/test/groovy/com/netflix/spinnaker/echo/notification/SlackNotificationAgentSpec.groovy: 62: The current scope already contains a variable of the name channel
 @ line 62, column 30.
       slack.sendMessage(*_) >> { message, channel, asUser ->
                                ^
2 errors

startup failed:
/echo/echo-notifications/src/test/groovy/com/netflix/spinnaker/echo/notification/SlackNotificationAgentSpec.groovy: 91: The current scope already contains a variable of the name channel
 @ line 91, column 30.
       slack.sendMessage(*_) >> { message, channel, asUser ->
                                ^
1 error
> Task :echo-notifications:compileTestGroovy FAILED

To fix this issue renamed the local variables to avoid the scope conflict with global variables.