[grafana] Make sidecar containers working

[sylvainOL]

When trying to use sidecars containers as init containers with restartPolicy set to Always (a.k.a. native sidecar), several small issues are occuring:

• every sidecar containers tries to bind the same port unless you set a startingProbe (#4039)
• dashboard init container as a u in its definition (#4033)
• METHOD is hardcoded for alerts and notifier containers, preventing them to be usable in sidecar mode (#4045)

This PR resolves the three issues by:

• setting a default health port different for each sidecar
• removing the not needed u
• allowing to choose METHOD on alerts and notifier containers when restartPolicy is defined and set to Always

Please note that the behaviour of all 4 sidecar containers is not exactly homogeneous and I just tried to replicate their behavior of what's actually done when started as regular container

closes #4039, #4033, #4045 and possible #4031

[CLAassistant]

All committers have signed the CLA.

[QuentinBisson]

@sylvainOL hey it looks like your PR has conflicts. Do you think you could double check the port configuration and fix the conflicts so we can get this merged?

[sylvainOL]

For the port I intentionnally didn't used the default one (8080) in any of the known sidecars.

This way, if someone add another kiwigrid sidecar and forget to set a value, it'll works out of the box.

[QuentinBisson]

Could you upgrade the chart once last time? Thank you