RFR: 1785: Do not always add CSR_UPDATE_MARKER when CSR bot finds withdrawn CSR Issue

[Zhao Song]

On Wed, 11 Jan 2023 19:30:04 GMT, Zhao Song <zsong at openjdk.org> wrote:

> In [SKARA-1728](https://bugs.openjdk.org/browse/SKARA-1728), I said that 'if we find a withdrawn pr, we need to add CSR_UPDATE_MARKER to the pr body.', yes, we need to add CSR_UPDATE_MARKER, but there is a prerequisite which is that our status message **doesn't** contain this withdrawn issue. Without the prerequisite, the CSR bot will always add CSR_UPDATE_MARKER when it finds a withdrawn CSR Issue and the pr body will be updated very frequently(looks like the bot go berserk). 
> 
> This issue is same as [SKARA-1673](https://bugs.openjdk.org/browse/SKARA-1673). I discovered this issue and fixed it, but I am silly enough to make the same mistake again.

Thanks for the review!

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PR: https://git.openjdk.org/skara/pull/1455