use nginx module from charmlibs

[PietroPasotti]

Enhancement Proposal

now that we abstracted the nginx module out into its own charmlib, we can remove the code out of this charm and use the shared lib instead.
Yay less code to maintain!

[lucabello]

This is being done in Tempo right now: canonical/tempo-operators#315

What we need to do for Pyroscope is:

• bump to the latest coordinated-workers
• remove the old nginx library from lib/charms/...

[MohamedKamalOthman]

Hi! I'd like to take this if it's still available.

[michaeldmitry]

Hi! I'd like to take this if it's still available.

Please :D

[MohamedKamalOthman]

I have opened this PR to bump coordinated workers version to 4.0.0. The necessary changes to the lib itself has already landed in another PR so what only needed to be done is to bump the version and run the tests.