[gold] Remove unused function common.OpenBoltDB().
[gold] Remove unused function common.OpenBoltDB().

Bug: skia:9349
Change-Id: I8cd1a3fc0fe51b3781e77c83cb744908386996ca
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/249235
Auto-Submit: Leandro Lovisolo <f558143c2568be8d55575d13f30a1fc5cb8009d5@google.com>
Commit-Queue: Kevin Lubick <7cdab2cfab351f23814786ba39716e90eed69047@google.com>
Reviewed-by: Kevin Lubick <7cdab2cfab351f23814786ba39716e90eed69047@google.com>

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