[llvm] [VPlan] Split handleEarlyExits into countable and uncountable passes. NFC (PR #206017)

[Luke Lau via llvm-commits]

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lukel97 wrote:

Thanks, that and the other review comments should be done in 65d0c160a4e9c359967fe5c8f960b2b3a4fa4fcd

https://github.com/llvm/llvm-project/pull/206017