This reverts commit 7549102bb727daecc51da84af39956b32fc41537.

Apparently I was wrong about
ActiveSupport::Notifications::Event#duration returning the duration in
seconds, instead it returns it in milliseconds already.

See merge request !2319

Get "Merge when build succeeds" to work when commits were pushed to MR
target branch while builds were running

The Merge when build succeeds service only merges when the MR is
mergeable (open, not WIP, no conflicts).

When the target branch is updated, all affected MRs have their merge
status set to `unchecked`, and the conflicts check will only happen
when `check_if_can_be_merged` is called, which happens when the MR page
is viewed.

When someone enables the automatic merge, the target branch is updated,
no-one views the MR page again, and the build succeeds, the mergeability
check will fail and the MR will not in fact be merged.

This MR makes sure `check_if_can_be_merged` is always called when MR
mergeability is checked.

See merge request !2304

Define a limited set of filters for SingleLinePipeline

Removes the following filters from its parent GfmPipeline:

- SyntaxHighlightFilter
- UploadLinkFilter
- TableOfContentsFilter
- LabelReferenceFilter
- TaskListFilter

Closes #1697 

See merge request !2257

Fix mentionable reference extraction caching.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/4130

Reverts https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/2120 and https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/2283

See merge request !2315

InfluxDB over UDP doesn't use authentication, thus there's no need for
these settings.

Transaction timings are also already stored in milliseconds, this keeps
things consistent.