[CLI] Move storage from app prefix to project/app prefix

[dmitsf]

What does this PR do?

We decided to move app storage prefix from app_id to project_id/app_id.
This PR makes the change. The environment variable LIGHTNING_STORAGE_PATH will be set inside the workflow container, and we will take the storage path from this environment variable.
If it's not specified, it will use the previous logic for defining app storage prefix.

Does your PR introduce any breaking changes? If yes, please list them.

Yes! App storage prefix will be different for new apps.
@rlizzo @panos-is @rusenask please take a look should we check do we have something from previously created app storages in the new logic, e.g. here: https://github.com/Lightning-AI/lightning/blob/master/src/lightning_app/storage/orchestrator.py#L90:L92 ?

We will deprecate old-way created storages in ~1 month.

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[rlizzo]

should we check do we have something from previously created app storages in the new logic, e.g. here: https://github.com/Lightning-AI/lightning/blob/master/src/lightning_app/storage/orchestrator.py#L90:L92 ?

I think for this we can actually get rid of that conditional and the old way of doing things entirely. This code would only ever run on newly created apps, not currently running apps that don't know the about the environment variable.

We just need to start injecting the env var on the cloud (before this is merged so that e2e tests can pass) and call it a day :)

[awaelchli]

Could we add a tiny test case (or modify existing one) just to make sure we understand what the exact value of LIGHTNING_STORAGE_PATH would look like and how it's returned from this function.

[awaelchli]

@dmitsf Just double checking, is the milestone correct, as this is a new addition/breaking change rather than a bugfix?

[dmitsf]

@dmitsf Just double checking, is the milestone correct, as this is a new addition/breaking change rather than a bugfix?

Thanks! Changed to 0.7.

[tchaton]

LGTM !

[codecov]

Codecov Report

Merging #14583 (66bfaee) into master (9769f57) will increase coverage by 24%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master   #14583     +/-   ##
=========================================
+ Coverage      61%      85%    +24%     
=========================================
  Files         381      327     -54     
  Lines       27588    25791   -1797     
=========================================
+ Hits        16899    21925   +5026     
+ Misses      10689     3866   -6823