Django configurable middleware index via env

[saichander17]

Description

The Django instrumentation middleware is being added at the first place right now and uses request.build_absolute_uri which internally calls get_host which validates if the host is from allowed hosts or not. As a result, users are facing issues in requests where they don't want this validation. In this PR, We allow users to configure where they can place otel middleware.

Fixes # (issue)
#1781

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

How Has This Been Tested?

At this point in time, it's not yet tested. I want to understand first if this is even the right approach before doing further work on this PR. If it is, I will go ahead and do additional work

Does This PR Require a Core Repo Change?

• Yes. - Link to PR:
• No.

Checklist (Yet to do):

See contributing.md for styleguide, changelog guidelines, and more.

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[linux-foundation-easycla]

• ❌ - login: @saichander17 / name: Sai Chander . The commit (de0ef0c, 9619c60, a76a0ec) is not authorized under a signed CLA. Please click here to be authorized. For further assistance with EasyCLA, please submit a support request ticket.

[saichander17]

Closing as #2834 is already in progress