Remove mutex from kbn pm bootstrap as all ci jobs are running isolated

[mistic]

This is a small PR as an effort to solve the problems we are having recurrently like:

00:00:12 /var/lib/jenkins/.kibana/node/8.11.4/lib/node_modules/yarn/lib/cli.js:77868
00:00:12     compromised = compromised || function (err) { throw err; };
00:00:12                                                   ^
00:00:12 
00:00:12 Error: Unable to update lock within the stale threshold
00:00:12     at options.fs.utimes (/var/lib/jenkins/.kibana/node/8.11.4/lib/node_modules/yarn/lib/cli.js:77790:66)
00:00:12     at FSReqWrap.oncomplete (fs.js:135:15)
00:00:13 
00:00:13 [bootstrap] failed:

[elasticmachine]

Pinging @elastic/kibana-operations

[joshdover]

Do we know exactly why this was added in the first place?

[mistic]

@joshdover according to @spalger there was a time when it was needed, but right now all the CI jobs are isolated in different vms, so I think it's secure to remove it!

[joshdover]

Great! On Nov 21, 2018 7:25 PM, "Tiago Costa" <notifications@github.com> wrote: @joshdover <https://github.com/joshdover> according to @spalger <https://github.com/spalger> there was a time when it was needed, but right now all the CI jobs are isolated in different vms, so I think it's secure to remove it! — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#26058 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ABuqENDwMyE2eSOOzHJ5prvrXJFm5LCwks5uxfz0gaJpZM4YugmJ> .

[elasticmachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request

[spalger]

LGTM

[mistic]

6.x: 1d662e5