Remove version generation approach.

Remove version generation approach.

Revert "Partially reland Auto-generate v8 version based on tags."

This reverts commit 0707afc863e14ad216fa2157f41fc35f86bd64b2.

Revert "Ensure tags are fetched when generating the V8 version."

This reverts commit ea6831e9de62ceade14b7baeb7d57c74a30a1f38.

Revert "Restrict tag-update for version generation to cached git repos."

This reverts commit c6641e138bb4a81b47f70e62bb9113c87b590a6f.

BUG=chromium:446166
LOG=n

Review URL: https://codereview.chromium.org/866263005

Cr-Commit-Position: refs/heads/master@{#26244}