Remove checkout bundle and job to improve reliability

[safern]

It seems like the azure devops bug where legs that started at a different time and a commit was introduced into the branch or target branch in between those legs, it would merge/checkout against a newer commit is fixed.

I did a test by:

1. Waiting for some legs to start and then pushing a commit to my branch (where I queued a manual build), then waited for other legs to start, they checked out the same commit (the one that was used to queue the build).
2. Waited for some PR legs to start, then once those legs finished the checkout, I pushed a commit (doc change) to the master branch, and waited for other legs (test legs, build legs) that didn't start immediatly, to start. Once they started, they merged my PR branch against the same commit (the commit that the HEAD pointed to in the target branch when I opened the PR).

As part of the surge we saw that this will help our reliability as sometimes we hit issues with the checkout bundle when downloading or uploading.

Also, the job was renamed to evaluate paths, and this will only run for pipelines that need it. At the moment only runtime and runtime-staging use the evaluate paths feature.

Test official build: https://dev.azure.com/dnceng/internal/_build/results?buildId=923883&view=results
Test CI build: https://dev.azure.com/dnceng/public/_build/results?buildId=924110&view=results

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Issue Details

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Test if removing checkout bundle works and checks out the same commit and merges against the same commit in the target branch for the PR across all the legs.

Author:	safern
Assignees:	-
Labels:	area-Infrastructure
Milestone:	-

[trylek]

Glad to finally see this workaround go, thanks Santi!

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