remove -i from go build

[graphaelli]

As reported in elastic/apm-server#2885 by @BlackYoup, go build -i doesn't seem to make much sense as we use it since go 1.10+. This change is needed to avoid reverting elastic/apm-server#2906 at the next beats update.

[urso]

Jenkins, test this.

[urso]

I don't know why go build -i is used. But I noticed that metricbeat (and others) unit tests are failing. Trying to restart tests didn't resolve it. Can you rebase on top of master, in case it's a problem with metricbeat itself?

@elastic/observability have we had problems with broken unit tests in metricbeat recently?

[exekias]

It's the first time I see this one, let me dig into it. I also see some Auditbeat tests failing.

Note: I think @elastic/observability is probably too wide, you can use @elastic/integrations better

[exekias]

I think this failure is related to file permissions, it would seem like BEAT_STRICT_PERMS=false is not being passed. On the other side, some more recent PRs are passing these tests (ie #14602).

@graphaelli could you please fix the double running issue to see if that's what's going on?

[graphaelli]

looks like everything is passing now

[ruflin]

-i was introduced to speed up build speed, see #4758 but as @graphaelli mentioned, not needed anymore.

[jalvz]

failure is unrelated, since Gil is out today i'll do the honours