Show cache alias instead of backend repr in calls table

[federicobond]

Description

This changes the values of the backend columns for cache calls in the Cache panel from <django.core.cache.backends.dummy.DummyCache object at 0x1063950a0> to default or the corresponding alias. This makes it much easier to identify which call is made to which backend when several cache backends share the same engine.

Before:

After:

Checklist:

• I have added the relevant tests for this change.
• I have added an item to the Pending section of docs/changes.rst.

[tim-schilling]

I feel like it's going to be hard for us to remember that this is effectively the old version of initialized_only=True. Do you have any ideas on making this more maintainable? [Specifically if Django changes its implementation upstream.]

The only idea I have is to use a cache._djdt_panel.record = functools.partial(cache._djdt_panel.record, alias=alias)

Though it makes me wonder if we need the panel on the cache at all. Seems like we could just store a _djdt_record function on the cache, where then the partial gets much cleaner.

[federicobond]

Though it makes me wonder if we need the panel on the cache at all. Seems like we could just store a _djdt_record function on the cache, where then the partial gets much cleaner.

We do not need the panel on the cache in the current code, it's just used a monkeypatch marker.

The only idea I have is to use a cache._djdt_panel.record = functools.partial(cache._djdt_panel.record, alias=alias)

I thought about something similar, but it needed more changes to the panel inner workings so I went with the most straightforward implementation to validate interest first. I could try a similar approach, storing a _djdt_record function.