Add CPU limitation

[vitaliy-guliy]

Signed-off-by: Vitaliy Gulyy vgulyy@redhat.com

What does this PR do?

Adds necessary CPU limitation for the plugin container configuration

Solves eclipse-che/che#16685

A sheet with a list of images used in plugins
https://docs.google.com/spreadsheets/d/1twoMLRC2A6YjTGiqXGvGvZP_M8GuKGydK75vhXQor2A/edit?usp=sharing

[che-bot]

Happy path tests passed.

[che-bot]

Happy path tests passed.

[amisevsk]

Generally LGTM but should be tested. In many cases we're providing a lower cpuLimit than plugins had to begin with -- e.g. on che.openshift.io, cpuLimit was/is set to 2x the memoryLimit. E.g. for the java plugin, this means going from 3 CPUs allocated to 0.5.

[l0rd]

A few comments:

1. setting the same limit for every plugin is useless, we already have defaults for this (CHE_WORKSPACE_SIDECAR_DEFAULT__CPU__LIMIT__CORES)
2. we should profile a plugins to see how much CPU it uses instead of randomly providing a value: workspaces get broken if we specify wrong values, it's better to set nothing instead.
3. we should specify requests too (in the case of this PR cpuRequest but in general memoryRequest would be helpful as well)
4. I would recommend to start with che-theia and che-machine-exec only and then, after we get some feedback and we see how it goes, iterate with other plugins as well

[azatsarynnyy]

Does it really work well?
The benchmarks @vzhukovs did in eclipse-che/che#18565 (comment) say the opposite - with 500m Che-Theia slows down significantly. See the Measurement 3.

[ericwill]

Obsoleted by #774