admission: enable admission control

[sumeerbhola]

Also updated existing roachtests that explicitly enabled
admission control to now disable admission control, so
that we can continue to compare performance of the two
settings.

Release note (ops change): The cluster settings affecting
the admission control system enablement are now set to
defaults that enable admission control.

[cockroach-teamcity]

This change is 

[sumeerbhola]

this is just to get a full run of unit tests and roachtests on CI

[jordanlewis]

If this passes basic tests, LGTM to merge and then revert Monday. Add annotations to roachperf like this: https://github.com/cockroachdb/roachperf/commit/7abd2af2bf5109376581c299c1a4a47f11354ee3

[RaduBerinde]

We should merge this soon. Along with it, won't we need to update the roachtests? The AdmissionControlEnabled flag would become a no-op, seems like we'd want to invert it and have some "noadmission" variants for a few tests.

[sumeerbhola]

Along with it, won't we need to update the roachtests? The AdmissionControlEnabled flag would become a no-op, seems like we'd want to invert it and have some "noadmission" variants for a few tests.

Done

TFTR!

Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @jordanlewis and @RaduBerinde)

[RaduBerinde]

Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @jordanlewis)

[sumeerbhola]

bors r+

[craig]

Build failed (retrying...):

• GitHub CI (Cockroach)

[craig]

Build succeeded:

• GitHub CI (Cockroach)