Update fluentd example to support new KFP V2 log archive

[Tomcli]

/kind feature

Description:
KFP V2 log archive will point to the main.log created by Argo. Since Tekton doesn't have a good way to store logs, we need to update our open source fluentd log archive example once the KFP V2 log archive feature is finished.

Additional information:
[Miscellaneous information that will assist in solving the issue.]

[Tomcli]

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