Revert "[release] Work-around deps-processing problem"

This reverts commit 5c84b6be.

Reason for revert: found another way

Original change's description:
> [release] Work-around deps-processing problem
> 
> TBR=tmrts@chromium.org
> 
> No-Try: true
> Bug: chromium:1106435
> Change-Id: I52657b4ee924e5e0133b0784bc12a0d75f94ec9d
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2304586
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Commit-Queue: Michael Achenbach <machenbach@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#68915}

TBR=machenbach@chromium.org,tmrts@chromium.org

Change-Id: I8925bef7525f453a9e2ee6cb298171813554b2a5
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:1106435
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2304810Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68922}

tools/release/auto_roll.py

@@ -50,7 +50,6 @@ class DetectLastRoll(Step):
       # TODO(machenbach): This should be part or the setdep api of
       # depot_tools.
       Var = lambda var: '%s'
-      Str = lambda s: s
       exec(FileToText(os.path.join(self._options.chromium, "DEPS")))
 
       # The revision rolled last.