Use updated patched azure SDK crates (#10036)

For a while already, we've been unable to update the Azure SDK crates
due to Azure adopting use of a non-tokio async runtime, see #7545.

The effort to upstream the fix got stalled, and I think it's better to
switch to a patched version of the SDK that is up to date.

Now we have a fork of the SDK under the neondatabase github org, to
which I have applied Conrad's rebased patches to:
https://github.com/neondatabase/azure-sdk-for-rust/tree/neon .

The existence of a fork will also help with shipping bulk delete support
before it's upstreamed (#7931).

Also, in related news, the Azure SDK has gotten a rift in development,
where the main branch pertains to a future, to-be-officially-blessed
release of the SDK, and the older versions, which we are currently
using, are on the `legacy` branch. Upstream doesn't really want patches
for the `legacy` branch any more, they want to focus on the `main`
efforts. However, even then, the `legacy` branch is still newer than
what we are having right now, so let's switch to `legacy` for now.

Depending on how long it takes, we can switch to the official version of
the SDK once it's released or switch to the upstream `main` branch if
there is changes we want before that.

As a nice side effect of this PR, we now use reqwest 0.12 everywhere,
dropping the dependency on version 0.11.

Fixes #7545